A2: Automatic Transmission

The most likely cause of metal flakes or shavings in a transmission’s oil pan is chipped gear teeth. Transmission gears are constantly engaging with one another, and over time, this friction can lead to wear, chipping, or breakage—resulting in metal debris collecting in the oil pan.

Although worn bands or clutches may also generate some metal particles, they typically do not produce the larger flakes or shavings associated with gear damage. Regardless of the source, the presence of metal debris in the oil pan is abnormal and should be promptly investigated to prevent further transmission damage.

The issue could lie with either the solenoid or the electrical circuit. The Transmission Control Module (TCM) activates solenoid B to engage first and second gears.

If engine RPM is lower than specified during a stall test, it may indicate low transmission or transaxle fluid. Insufficient fluid can lead to reduced hydraulic pressure, causing the transmission to slip or fail to engage properly—resulting in decreased engine speed.

Technician B’s suggestion that a slipping torque converter clutch is to blame is incorrect in this case. A slipping torque converter clutch would usually cause higher, not lower, RPM during a stall test. Therefore, Technician B’s diagnosis does not apply to this situation.

An unbalanced torque converter can definitely lead to vibration problems in a vehicle. Since the torque converter transfers power from the engine to the transmission, any imbalance can create engine vibrations that are felt throughout the vehicle. However, a damaged or worn output shaft can also cause similar issues. The output shaft delivers power from the transmission to the wheels, and if it’s faulty, it can result in noticeable vibrations during operation.

The gear selector controls the transmission circuit through the manual valve, which is connected via the shift cable. This linkage is usually adjustable. If it’s misadjusted, the manual valve may direct line pressure into the wrong circuit.

As a result, the vehicle might move unexpectedly while in neutral, placing stress on the transmission’s clutch and potentially causing damage or overheating. To prevent this, inspect and properly adjust the shift cable and linkage. This adjustment is essential for safe operation. Always consult the manufacturer’s manual and check for applicable Technical Service Bulletins (TSBs) before making any changes.

The overdrive gear ratio is the one that produces the highest output shaft speed relative to engine speed. In the chart provided, the overdrive ratio is 0.852:1, meaning the output shaft turns once for every 0.852 rotations of the engine. Since this is the highest (numerically lowest) ratio in the chart, it best represents the overdrive gear.

Marking the front drive axles in relation to the front hubs is not a required step during transmission removal and replacement. While it’s important to handle the axles carefully to avoid damage, marking their position relative to the hubs is not a standard part of the procedure.

However, when removing the driveshaft, you should mark its position in relation to the differential flange. This ensures proper alignment during reinstallation and helps prevent driveline vibrations.

To safely remove the transmission, use an engine support fixture or other appropriate support to hold the engine in place. This prevents unnecessary strain on connected components and allows for smoother removal.

Additionally, always disconnect the negative battery cable before beginning any transmission work. This is a critical safety step to avoid electrical shorts and create a safer work environment.

If the input shaft of an automatic transmission is binding and has no endplay after a rebuild, simply installing the transmission and operating the vehicle will not resolve the issue. The binding is likely due to incorrect assembly, improper clearance, or damaged components, and further inspection and repair are necessary.

Technician B’s suggestion that a thinner selective washer may be needed is valid. Selective washers are used to adjust input shaft endplay, and if the endplay is too tight, it can cause the shaft to bind, affecting transmission performance. Installing a thinner washer can restore proper endplay and help eliminate the binding issue.

Overfilling the transmission can lead to excessive fluid pressure, which may force fluid out through the dipstick tube and cause a leak. An overly high fluid level can also cause the fluid to aerate and foam, increasing the likelihood of leakage from the dipstick tube.

Likewise, aerated or foamy fluid can reduce the transmission’s ability to lubricate and cool properly. This can result in overheating and potential damage, which may also lead to fluid leaks.

Therefore, both Technician A and Technician B could be correct. Further inspection is necessary to determine the exact cause of the transmission fluid leak.

A clogged transmission filter is one of the most common problems revealed during an automatic transmission pressure test. When the filter is dirty, it restricts the flow of hydraulic fluid, causing pressure to rise abnormally within the system. These pressure irregularities can be quickly identified at designated test points during the pressure test.

The most likely reason the MIL is on and the transmission only functions in third and reverse gears is that the vehicle has entered Limp Mode.

Limp Mode is a built-in safety feature in modern automatic transmissions designed to prevent further damage when a serious fault is detected. When the Transmission Control Module (TCM) identifies a problem that could harm the transmission, it restricts gear operation—usually to third and reverse—to allow the driver to safely reach a repair facility.

One of the most common triggers for Limp Mode is low line pressure, which can result from a clogged transmission filter, a failing pump, or a faulty pressure control solenoid. Low line pressure often leads to symptoms such as slipping, delayed engagement, or harsh shifting.

Although adaptive learning or high line pressure can cause shifting issues, they typically do not restrict the transmission to just third and reverse gears. For this reason, Limp Mode caused by low line pressure is the most likely cause of the condition described.

Technician B believes the noise may be coming from the oil pump assembly and recommends an off-vehicle inspection. The oil pump is responsible for circulating transmission fluid and maintaining the hydraulic pressure needed for proper operation. If it’s damaged or malfunctioning, it can produce unusual noises within the transmission.

Technician A suggests the control valve could be the source of the noise and also requires off-vehicle service. While the control valve regulates fluid flow and direction, it is less likely to cause distinct noises compared to a faulty oil pump. Therefore, Technician B’s diagnosis is more plausible in this scenario.

The flex plate check is not part of the preliminary diagnostics for an electronically controlled automatic transmission. In contrast, tests such as the fluid check, line pressure test, and stall test are commonly used to identify issues within these systems.

The flex plate, which connects the engine to the transmission, is a mechanical component and not part of the electronic control system. As a result, it is not typically included in the initial diagnostic procedures for electronically controlled transmissions.

A dial indicator is the tool most commonly used to measure ring gear backlash. It provides precise measurements of small movements, making it ideal for checking clearances and tolerances in automotive applications.

The other tools listed serve different purposes: a straightedge and feeler gauge are used to measure flatness or small gaps, an inch-pound torque wrench is for checking torque values, and an outside micrometer measures the diameter of round components. These tools are not typically used for measuring ring gear backlash.

Automatic transaxles depend on the proper amount of transmission fluid to lubricate and cool internal components such as clutches, bands, and gears. Low fluid levels can cause a drop in hydraulic pressure, leading to slipping or inconsistent engagement.

During cornering, centrifugal force can cause the fluid to shift within the transaxle. If the fluid level is already low, this movement may result in a temporary loss of pressure or poor lubrication, causing the clutches or bands to slip. This often presents as hesitation or slipping while turning.

Milky fluid in the transmission cooler is a clear sign of contamination, typically caused by a mix of transmission fluid (ATF) and engine coolant. This cross-contamination occurs when a leak develops within the transmission cooler—a heat exchanger designed to keep the transmission fluid at a safe operating temperature. The cooler is usually located inside the radiator or in a separate unit, with coolant and transmission fluid flowing through isolated chambers.

If the internal barrier fails, coolant can enter the ATF system. Because coolant contains water and ethylene glycol—both hygroscopic substances—it attracts moisture and reacts with the oil in the transmission fluid, forming a milky, emulsified mixture. This contamination can severely affect transmission performance and should be addressed immediately.

Both technicians are correct. Technician A is right in stating that the transmission oil pump is the source of all fluid flow in an automatic transmission. It generates the hydraulic pressure needed to circulate fluid through the transmission and its internal circuits.

Technician B is also correct. Hydraulic flow charts illustrate how fluid moves through solenoids, valves, and various oil circuits within the transmission. These charts are valuable diagnostic tools that help technicians pinpoint issues within the hydraulic system.

When removing a torque converter from an automatic transmission, the technician should carefully inspect the converter’s hub for any signs of damage, such as discoloration, nicks, scratches, or burrs. These issues may point to underlying problems with either the torque converter or the transmission. It’s also important to measure how deep the torque converter sits within the transmission’s bell housing before removal. This measurement helps ensure correct alignment and installation during reassembly.

The MAP (Manifold Absolute Pressure) sensor monitors the pressure within the intake manifold to provide the engine control unit (ECU) with data about engine load. This information is essential for adjusting the fuel-to-air ratio, ignition timing, and transmission shift points. By accurately reporting engine load, the MAP sensor helps optimize both engine performance and transmission response.

The MAF (Mass Air Flow) sensor measures the amount of air entering the engine, allowing the ECU to calculate the precise amount of fuel needed for efficient combustion. Proper fuel metering is critical for maintaining engine performance, and the transmission adjusts its shifting patterns based on this output.

The TPS (Throttle Position Sensor) tracks the position of the throttle plate, reflecting the driver’s acceleration input. The ECU uses this signal to fine-tune fuel injection and ignition timing, while the Transmission Control Module (TCM) relies on it to determine appropriate shift points and adapt transmission behavior to match driving conditions.

A faulty shift interlock solenoid is a common reason why an automatic transmission won’t shift out of PARK. This solenoid is controlled by the brake pedal and prevents the shifter from moving unless the brake is pressed. If the solenoid fails, it may not release the shifter even when the brake pedal is properly engaged.

However, a malfunctioning brake switch can also be the culprit. The brake switch sends the signal to activate the shift interlock solenoid when the brake pedal is pressed. If the switch is defective, it may fail to send this signal, keeping the shifter locked in PARK.

Both Technician A and Technician B are partially correct.

Technician A is right that when the torque converter’s lockup clutch engages, the turbine and impeller rotate at the same speed. This occurs because the lockup clutch eliminates the fluid coupling by creating a direct mechanical connection between the two components.

Technician B is also correct in stating that the lockup clutch engages during the coupling phase. In this phase, the impeller and turbine are already closely matched in speed due to fluid coupling. Once certain driving conditions are met—typically at higher speeds—the lockup clutch engages to eliminate slippage and improve efficiency.

Both Technician A and Technician B are correct.

The Electronic Pressure Control (EPC) system in an automatic transmission uses electronic signals to regulate hydraulic pressure. It adjusts line pressure based on factors like engine speed and torque, ensuring the correct amount of pressure is applied to clutches and bands for smooth and precise gear shifts.

This system often includes a variable force solenoid, which is controlled by the Transmission Control Module (TCM). The solenoid modulates the hydraulic pressure by adjusting the force on the pressure control valve, allowing the EPC system to maintain optimal line pressure throughout various driving conditions.

The transmission oil pump circulates fluid throughout the automatic transmission, and its pump bushing supports the input shaft that links the torque converter to the transmission. If the pump’s front seal is leaking and the bushing is worn, transmission fluid may escape, leading to a drop in hydraulic pressure. This can result in slipping or failure to engage gears properly.

Technician A suggests that loose flexplate bolts could be the cause. Since the flexplate connects the engine to the torque converter and also mounts the starter motor, loose bolts can cause excessive movement. This movement may stress the input shaft, leading to wear on the pump bushing and front seal.

Technician B attributes the issue to a misaligned transmission bellhousing. The bellhousing ensures proper alignment between the engine, torque converter, and transmission input shaft. If misaligned, it can offset the input shaft, accelerating wear on the pump bushing and front seal.

Therefore, both Technician A and Technician B may be correct in identifying contributing factors to the problem.

Both technicians could be correct, as both the Transmission Fluid Temperature (TFT) sensor and the Engine Coolant Temperature (ECT) sensor can influence torque converter clutch operation. The TFT sensor sends data to the Transmission Control Module (TCM) regarding fluid temperature, which helps determine when the torque converter clutch should engage. Similarly, the ECT sensor provides the Engine Control Module (ECM) with engine coolant temperature information, which can impact both engine and transmission performance.

Given that both sensors play a role, further diagnostic testing is needed to identify the exact cause of the issue.

A Single Pole Double Throw (SPDT) electromechanical relay is an electrical switch made up of a coil, an armature, and a set of contacts. It features one input terminal, known as the common terminal (COM), and two output terminals: one normally open (NO) and one normally closed (NC).

Direct programming involves connecting the EEPROM directly to a programmer, which transfers data straight to the memory chip.

Off-board programming requires removing the EEPROM from the circuit board and programming it separately with a dedicated device.

Remote programming allows the EEPROM to be reprogrammed while still installed on the board, using a specialized tool that connects remotely.

“Indirect programming” is not a standard method used for reprogramming EEPROMs.

Both the vehicle speed sensor and the parking pawl are connected to the output shaft of an automatic transmission. The vehicle speed sensor is driven by the output shaft to measure the vehicle’s speed, while the parking pawl locks the output shaft in place to hold the transmission in Park.

The most likely cause of low line pressure at idle in all ranges in an electronically controlled automatic transmission is a faulty oil pump pressure regulator. This component controls the output of the oil pump to maintain proper hydraulic pressure throughout the transmission. If it malfunctions, it can lead to consistently low pressure, resulting in shifting problems and reduced transmission performance.

Although issues such as a faulty ATF temperature sensor, an improperly adjusted throttle position (TP) sensor, or an open circuit in the dropping resistor can affect transmission performance, they are less likely to cause low pressure at idle across all ranges. Accurate diagnosis is essential to identify the root cause and ensure the correct repair.

Slipping and engine flare in synchronous transmissions can result from incorrect shift timing. These transmissions use synchronizers to match gear speeds during shifts. When shift timing is off—such as the synchronizers engaging too slowly or at the wrong moment—proper gear engagement may not occur. This incomplete engagement leads to slipping, where power isn’t fully transferred, causing the engine to rev higher (engine flare) without a corresponding increase in vehicle speed.

An “open shift interlock solenoid” is less likely to cause delayed engagement when shifting from Park to Drive or Reverse in an automatic transmission. The shift interlock solenoid serves as a safety mechanism that prevents the shifter from moving out of Park unless the brake pedal is pressed. If it fails, it typically prevents the shifter from moving at all, rather than causing a delay in gear engagement.

In contrast, delayed engagement is more commonly caused by issues such as a clogged transmission oil filter, low hydraulic pressure, or oil pump starvation—factors that directly affect the transmission’s ability to engage gears promptly.

Technician B is correct in identifying the control valve as the likely source of the issue, and diagnosing or repairing it typically requires removing the transmission—making it an off-vehicle procedure. In contrast, Technician A’s claim that the oil pump assembly also requires an off-vehicle procedure is incorrect.

The oil pump assembly is located inside the transmission and can often be accessed and removed without fully removing the transmission from the vehicle. This makes it an on-vehicle procedure. On the other hand, the control valve is part of the valve body, which generally requires transmission removal for proper access—making it an off-vehicle task.

Therefore, if a technician suspects the oil pump assembly is causing the problem, it can be inspected and serviced more easily without removing the transmission, saving time and effort compared to addressing issues with the control valve.

When shifting from Neutral to Drive, the forward clutch engages to connect the transmission’s input shaft to the output shaft, enabling forward movement of the vehicle.

If the forward clutch has worn or damaged friction plates, or if the apply piston is malfunctioning, it can cause a harsh or abrupt engagement when shifting into Drive. This results in the noticeable “shock” or jolt sensation experienced during the shift.

Resolving this issue requires an off-vehicle repair. The transmission must be disassembled to inspect the forward clutch components for wear or damage. Depending on the findings, the clutch may need to be repaired or replaced, along with related parts such as the apply piston or seals.

Both Technician A and Technician B are correct.

Ball-type check valves are commonly used in valve body hydraulic circuits to allow one-way fluid flow. These valves typically feature a small ball that rests in a seat, permitting fluid to pass in one direction while blocking flow in the opposite direction.

Technician A is also correct in stating that the seat for these ball-type check valves is often located on the valve body separator plate. This thin metal plate sits between the valve body and the transmission case, and it contains passages that route hydraulic fluid to various components within the valve body.

The governor typically controls how transmission shift points relate to vehicle speed. It monitors the output shaft speed—either mechanically or electronically—and signals the transmission control module when the vehicle reaches specific speeds to initiate gear shifts.

In contrast, the throttle valve regulates the air-fuel mixture entering the engine, affecting engine speed but not directly determining shift points based on vehicle speed. In an automatic transmission, throttle pressure generally corresponds to engine load, which reflects the vehicle’s overall load but does not serve as the primary input for shift timing related to speed.

If a three-speed automatic transmission produces a whining noise that stops after shifting into third gear, the most likely cause is an issue with the planetary gear set.

The planetary gear set is a critical component that enables various gear ratios and torque multiplication. It includes sun gears, planet gears, and a ring gear, all working together in a precise arrangement to deliver different speeds and torque levels.

Worn or damaged gears within this assembly can generate abnormal noises during operation. The fact that the whining noise disappears in third gear suggests the issue is tied to gear interactions used only in the lower ranges, indicating a specific problem within the planetary gear set.

Neither Technician A nor Technician B is correct.

While many automatic transmissions use a dipstick to check fluid levels, some newer or sealed transmissions require specialized procedures and tools to measure fluid accurately. The absence of a dipstick does not indicate a problem—it simply reflects the design of that specific transmission model.

If, after bringing the transmission to operating temperature and removing the inspection plug, no fluid leaks from the outlet, it may indicate that the fluid level is correct for that system. However, it’s essential to consult the manufacturer’s service manual to confirm the correct procedure and specifications for checking fluid levels.

Additionally, the lack of fluid leakage does not necessarily mean the transmission is overheating. Overheating can result from various issues such as clogged fluid passages, a faulty cooling system, or internal transmission problems. To accurately determine if the transmission is overheating, the fluid temperature must be measured and compared to the manufacturer’s recommended operating range.

The stator in a torque converter is equipped with a one-way clutch that allows it to rotate freely in one direction while preventing rotation in the opposite direction. Positioned between the impeller and turbine, the stator’s main role is to redirect transmission fluid as it exits the turbine and returns to the impeller. This redirection significantly enhances torque multiplication and overall efficiency.

The one-way clutch enables the stator to spin when it supports fluid flow and torque multiplication but locks it in place when its rotation would create drag, ensuring optimal performance of the torque converter.

All of the listed factors can contribute to harsh shifting in a planetary gearset with an automated transmission.

A faulty Electronic Pressure Control (EPC) solenoid can lead to harsh shifts by misregulating the hydraulic pressure needed for smooth gear changes. If the solenoid malfunctions, it may cause the transmission to shift too aggressively or inconsistently.

Similarly, a sticking pressure regulating valve can disrupt proper pressure control within the system. If the valve becomes stuck, it can prevent the transmission from maintaining the correct pressure, resulting in abrupt or delayed shifts.

Contaminated or degraded transmission fluid is another common cause. As fluid ages, it can accumulate debris and lose its effectiveness, leading to poor lubrication and hydraulic performance—both of which contribute to harsh or erratic shifting.

Both Technician A and Technician B are correct.

Diagnostic Trouble Code (DTC) P0705 is triggered when the Transmission Control Module (TCM) or Powertrain Control Module (PCM) does not receive the correct voltage signal from the Park/Neutral Position (PNP) switch. Technician A is correct in stating that the code is set due to the absence of the proper signal from the PNP switch, which can result from issues such as a faulty switch, wiring problems, or a malfunctioning control module.

Technician B is also correct in noting that a short or open circuit in the PNP switch circuit can cause this loss of signal. Therefore, both the signal issue and potential circuit faults are valid causes of the P0705 code.

A variable-displacement vane pump is commonly used in automatic transmissions because it can adjust its flow rate to meet the system’s changing demands. Automatic transmissions rely on a consistent supply of pressurized fluid for proper operation, especially during gear shifts and varying load conditions.

This type of pump works by altering the angle of its vanes, which changes the volume of fluid displaced with each rotation. By adjusting the vane angle, the pump can increase or decrease fluid flow as needed, providing precise control over hydraulic pressure. Its efficiency and adaptability make the variable-displacement vane pump a preferred choice in modern automatic transmissions.

Automatic transmissions generally do not use a crankshaft pilot bearing. This component is typically found in manual transmission systems, where it supports the input shaft and ensures smooth rotation. Installed in the center of the flywheel or flexplate, the pilot bearing allows the manual transmission’s input shaft to align and rotate properly with the engine’s crankshaft.

Both Technician A and Technician B could be correct, as a faulty accumulator or a broken accumulator spring can lead to difficulty shifting into second gear in an automatic transmission.

The accumulator is a hydraulic component designed to smooth out and regulate line pressure during gear changes. If it malfunctions, it may fail to supply the proper pressure needed for a smooth transition into second gear, causing shift hesitation or harshness.

Likewise, a broken spring inside the accumulator can disrupt pressure regulation, making it difficult for the transmission to engage second gear properly. Both issues can result in similar shifting problems.

Brown or dark brown transmission fluid indicates that the fluid has lost its viscosity and is undergoing oxidation. Oxidation occurs when the fluid becomes aerated, reducing its ability to lubricate and protect the transmission. If your transmission fluid has turned this color, it should be changed immediately.

Overfilling or underfilling can accelerate oxidation, darkening the fluid. Water contamination may cause the fluid to appear lighter or take on a pinkish hue, while friction material wear can turn it dark brown or even black. Additionally, contamination from engine coolant can result in a milky or frothy appearance.

However, fluid color alone is not always a reliable diagnostic tool. Different types of contamination can produce similar visual changes. Other signs—such as burnt odors, erratic shifting, or slipping—should also be considered when assessing potential transmission issues.

A transmission brake band is a braking component used in automatic transmissions. It wraps around a drum or rotating element and is applied using hydraulic pressure to stop or hold that component in place. Its primary function is to act as a stopping or holding device—it does not engage or drive the members of the planetary gear set.

If the transmission fluid appears milky, it likely indicates contamination from water or coolant mixing with the ATF. This is most often caused by a leak in the transmission cooler, which is typically located inside the radiator. When the cooler fails, coolant can enter the transmission fluid, resulting in the milky appearance.

Among the possible causes, an oil cooler leak is the most probable—not a slipping band, overheating, or oxidation. It’s crucial to address this issue promptly, as operating the transmission with contaminated fluid can cause significant internal damage.

Both technicians are correct.

Technician A is right in stating that a multiple friction disc clutch in an automatic transmission can drive a component of the planetary gearset. These clutches engage and disengage specific gearset members, allowing for changes in gear ratios during operation.

Technician B is also correct. A multiple friction disc clutch can serve to ground a planetary gearset member to the transmission case. When applied, the clutch locks the rotating component to the stationary case, effectively holding it in place. This mechanical grounding is essential for proper gear function and is unrelated to electrical grounding.

Weak governor spring tension is unlikely to cause excessive speed during shifting in an automatic transaxle. Instead, it typically leads to delayed upshifts and slower shift timing.

However, a sticking governor valve can prevent the transmission from shifting at the correct speed, causing the vehicle to reach higher speeds before upshifting. Similarly, excessive governor spring tension can lead to overly aggressive or early governor response, resulting in abrupt shifting and increased speed during gear changes.

Additionally, worn governor weights or pins can interfere with the governor’s ability to accurately sense vehicle speed. If these components are worn or sluggish, they can delay or disrupt shift timing, potentially contributing to excessive speed during shifts.

The transmission range sensor, also known as the neutral safety switch or gear position sensor, is responsible for detecting the position of the gear selector and allowing the vehicle to start only in “Park” or “Neutral” positions. If the sensor is faulty, it may prevent the vehicle from starting in the correct gear, but it does not directly affect the starter’s operation.
Technician B is also correct. An ohmmeter is a device used to measure electrical resistance, and it can be used to test the continuity and resistance of various components, including the transmission range sensor. By measuring the resistance across different terminals of the sensor, one can determine if it is functioning within the specified range or if it is faulty.

This is the connector used in the signal circuit of the Throttle Position (TP) sensor.

In wiring diagrams, a splice is indicated by a solid black dot and represents the connection point where two or more wires are joined. In the TP sensor’s signal circuit, this connector is part of that splice. The schematic symbol showing this connection uses the black dot to illustrate the joined wires.

Additionally, the reference voltage circuit is labeled as 5V ref, indicating a 5-volt supply used as a reference for sensor operation.

Technician A is correct in recommending that the battery voltage be checked first. The battery supplies power to all transaxle components, including the shift solenoids. If the voltage is low, it can disrupt solenoid operation and prevent the transaxle from shifting into fourth gear.

Technician B is also right in advising a basic inspection of hoses and wiring. However, this step should follow the battery check. If the battery voltage is within the normal range, then wiring or hose issues become more likely as potential causes.

Differential side bearings support the differential gears within the transaxle. When these bearings become worn or damaged, they can produce a growling or rumbling noise that intensifies as vehicle speed increases due to higher rotational forces. This makes Technician A’s statement plausible.

On the other hand, differential spider gears (also called pinion gears) are located inside the differential and help distribute torque between the drive wheels. If they are worn or damaged, they typically cause clunking or clicking noises, rather than the low-pitched growl associated with bearing wear. Therefore, Technician B’s statement is less likely to be correct in this scenario.

Technician A is correct. Transmission fluid (TF) that is not changed regularly can become contaminated, leading to the buildup of tarnish and debris on the transmission case and internal components. This buildup can clog solenoids and valves, causing them to stick. A sticking solenoid may result in the vehicle being stuck in gear or remaining in neutral.

Technician B is incorrect. Before replacing a solenoid, it’s important to perform proper diagnostics using a bidirectional scan tool and a multimeter. These tools allow technicians to test the solenoid and its circuit to determine whether replacement is actually needed.

When removing a transmission, several components typically need to be removed, though the exact steps may vary depending on the vehicle and transmission type. Common parts that are usually removed include:

1. Driveshaft

2. Transmission cooler lines

3. Transmission mounts

4. Starter motor

5. Shift linkage or cable

6. Electrical connectors and sensors

7. Torque converter bolts (if applicable)

8. Bellhousing bolts

9. Inspection cover

While the transmission fluid pan and filter may be removed during service, they are not always necessary for transmission removal. Importantly, the flexplate does not need to be removed when removing the transmission.

Among the first priorities should be removing the transmission cooler lines, the inspection cover, and the driveshaft, as these steps provide access and clearance for the rest of the removal process.

Technician A suggests replacing the sensors and clearing the fault codes. While replacing faulty sensors may be necessary, simply erasing the codes does not resolve the underlying cause of the gear hunting or shift timing issues, and may result in recurring problems.

Technician B recommends inspecting the circuits connected to the sensors and shift solenoids, which is a more thorough and effective approach. Electrical issues such as damaged wiring, poor connections, or shorts can cause sensor and solenoid malfunctions. By addressing potential circuit faults, Technician B’s method targets the root cause of the issue, improving the chances of a lasting and accurate repair.

The 2-4 band is designed to work with manual braking. In contrast, the forward clutch, third clutch, and direct clutch do not serve a braking function and remain engaged during all forward gear ranges.

Both Technician A and Technician B are correct.

Technician A is right in stating that petroleum-based automatic transmission fluid (ATF) is usually dyed red to distinguish it from other vehicle fluids. Over time and under normal operating conditions, the fluid can darken to a brownish color due to heat exposure.

Technician B is also correct that excessively dark or burnt-smelling ATF may indicate a problem, such as a slipping clutch or band. Slipping generates excessive heat, which can burn the fluid and degrade its performance. This condition suggests potential internal issues and should be inspected by a qualified technician.

Both technicians are correct. The lockup clutch creates a direct mechanical link between the engine and transmission, eliminating the fluid coupling and improving efficiency. This engagement occurs during the coupling phase, when the turbine is spinning at about 90% of the impeller’s speed.

The impeller, also known as the pump, rotates with the engine and pushes transmission fluid onto the turbine vanes. As engine speed increases, the fluid force causes the turbine—and thus the transmission’s input shaft—to turn.

Technician A is incorrect in stating that shift solenoids are hydraulically controlled devices. In modern automatic transmissions, shift solenoids are electronically controlled actuators that manage gear changes by regulating hydraulic fluid flow.

Technician B is correct. Shift solenoids are controlled by the vehicle’s transmission control module (TCM) and can be diagnosed using a scan tool. The scanner communicates with the TCM to retrieve fault codes and monitor real-time data related to solenoid function. If a solenoid malfunctions, the TCM typically stores a diagnostic trouble code (DTC), which helps technicians pinpoint and resolve the issue efficiently.

Technician A suggests that a binding universal joint could lead to wear and deterioration of the extension housing seal and bushing. This is a valid point, as a binding U-joint can place excessive stress on drivetrain components. When the joint doesn’t move smoothly, it can cause vibrations and uneven shaft movement, which may accelerate wear on the seal and bushing.

Technician B attributes the problem to excessive output shaft endplay, which refers to the axial movement of the transmission’s output shaft. While too much endplay can cause misalignment and stress on the extension housing components, it is less likely to be the sole cause of bushing deterioration. Excessive endplay is more often linked to internal wear, such as worn bearings or other internal transmission damage.

Therefore, both technicians raise valid concerns, but the binding universal joint is a more likely primary cause of the seal and bushing wear.

The oil pump plays a crucial role in circulating transmission fluid to ensure proper lubrication and maintain hydraulic pressure for transmission operation. If the oil pump is failing, it can cause insufficient fluid flow and pressure, which may result in a noticeable whining noise.

As engine speed increases, the pump rotates faster, making any internal issues—such as worn gears or bearings—more pronounced. These damaged components can produce a whining sound, especially under higher RPMs. Additionally, a malfunctioning pump that fails to deliver an adequate fluid supply can also contribute to the noise and affect overall transmission performance.