A4: Suspension & Steering

The camshaft position sensor is typically found near the cylinder head or valve cover, often mounted directly on the camshaft or on a bracket attached to it. In some cases, it may be located on the timing belt or chain cover, though this is less common.

This sensor provides the engine control unit (ECU) with precise information about the camshaft’s position. The ECU uses this data to manage ignition timing and fuel injection, ensuring efficient engine performance and proper timing of combustion events.

Feathering on the tread of a vehicle’s left front tire is most commonly caused by an incorrect toe setting. Toe refers to the angle of the tires relative to each other when viewed from above. If the toe is not set to the manufacturer’s specifications, it can lead to uneven wear, resulting in a feathered or saw-tooth pattern on the edge of the tread, where one side of each tread block is more worn than the other.

While camber can also influence tire wear, it generally causes even wear across the inner or outer edge of the tire rather than feathering. Caster misalignment and worn struts are less likely to be the primary cause of this specific wear pattern.

A binding wheel bearing is the least likely cause of memory steer—a condition where the steering wheel fails to return to center after completing a turn. Memory steer is typically caused by binding or worn components within the steering or suspension system.

Components such as the ball joint, steering gear, and upper strut mount are more directly involved in steering function and are more likely to cause memory steer when they become worn or damaged. In contrast, the wheel bearing supports the wheel on the axle and, while a worn bearing may lead to wheel wobble or noise, it does not directly affect the steering system’s ability to return to center.

The statement that oil leakage will cause a vehicle to fail a bounce test is not accurate when referring to a conventional shock absorber.

A conventional shock absorber is a hydraulic device designed to control suspension movement and keep the tires in contact with the road. It operates using hydraulic fluid, not air. While oil leakage is a sign of wear or internal damage, it does not immediately cause a vehicle to fail a bounce test.

A bounce test is used to evaluate shock absorber performance by pressing down on the vehicle and observing how many times it rebounds. If the vehicle bounces more than once or twice, the shocks are likely worn. Although oil leakage reduces the shock’s ability to dampen motion effectively, the vehicle will still bounce—indicating that the shocks are not functioning properly—not that the oil leak directly causes the failure of the test.

Technician A is correct: If a vehicle has more positive camber on one side, the tire on that side will contact the road more on its outer edge. This uneven contact creates a pulling effect toward the side with greater positive camber.

Technician B is also correct: Excessive negative camber causes the tire to ride on its inside edge, leading to uneven tread wear and accelerated wear on the inner portion of the tire.

When a vehicle turns left, its weight shifts to the right side, placing additional load on the right front wheel bearing. If that bearing is worn or damaged, the increased stress will cause the noise to become more pronounced during left turns.

Tire pitch naturally changes when moving from one surface to another, a characteristic common to all tires. However, this change is especially noticeable with cupped or scalloped tires, as the uneven tread pattern amplifies the sound.

Some air shocks can be inflated using a shop air hose, but it’s essential to follow the manufacturer’s specifications to avoid exceeding the recommended pressure. Over-pressurizing can damage the shock absorber or other suspension components.

If an air shock begins to lose pressure, the issue may stem from a leaking airline or valve, which can often be repaired or replaced. However, if the loss of pressure is caused by internal failure—such as a damaged seal or piston—the shock absorber will likely need to be replaced.

Electric Power Steering (EPS) systems rely on input from both the steering torque sensor and the vehicle speed sensor to operate the electric motor effectively. The torque sensor detects the amount of force applied to the steering wheel, while the vehicle speed sensor informs the system of how fast the vehicle is moving—allowing the EPS to adjust steering assist accordingly.

Technician B is also correct in recommending the use of a scan tool to retrieve fault codes. When a malfunction occurs within the EPS system, a diagnostic trouble code is typically stored. Using a scan tool to read these codes is essential for accurately identifying and addressing the root cause of the problem.

Camber refers to the vertical angle of the wheel relative to the ground—specifically, the tilt of the wheel inward or outward from the vehicle’s vertical axis. Adjusting the camber on the left front strut can affect the vehicle’s toe settings, which determine the direction the tires point in the horizontal plane.

When camber is changed on one side, it can alter the suspension geometry, which in turn can influence toe alignment on that side. For example, adjusting camber on the left front strut may lead to changes in the left toe setting and impact the total toe, which is the combined toe angle of both front wheels.

When viewed from the front of the vehicle, if the top of the tire tilts outward, it is referred to as positive camber. If the top of the tire tilts inward, it is referred to as negative camber

The chart indicates that the vehicle has excessive camber on the right front wheel, exceeding the specified tolerance of 0.5 degrees. Since a vehicle tends to pull toward the side with greater positive camber, this condition is likely causing it to pull to the right. The caster readings, however, are within acceptable limits.

Ball joints are essential parts of the suspension system that enable both vertical wheel movement and steering control. When a ball joint binds or sticks, it can restrict wheel movement and prevent the steering wheel from returning to center after a turn.

Although loose inner or outer tie rod ends or worn stabilizer bar bushings can impact vehicle handling and stability, they are less likely to be the cause of a steering wheel that fails to self-center.

Worn stabilizer bar bushings are the most likely cause of noticeable body sway when a vehicle turns, even at low speeds. The stabilizer bar, or sway bar, is a key suspension component designed to minimize body roll during cornering. It connects to the suspension system through bushings, which can deteriorate over time. When these bushings wear out, the stabilizer bar may become loose or ineffective, resulting in excessive body lean during turns.

Although issues like a binding ball joint or a worn idler arm can lead to poor handling—such as steering wander or uneven tire wear—they are less likely to cause body sway specifically. Similarly, worn control arm bushings may lead to general suspension instability and vibrations, but not the distinct leaning effect seen in turns caused by worn stabilizer bar bushings.

When a vehicle demands excessive steering effort—even with a properly tensioned power steering belt and a full fluid reservoir—a likely cause could be a seized idler arm. The idler arm plays a key role in supporting and guiding the steering linkage. If it becomes stiff or stuck, it can restrict the smooth movement of the steering system. This added resistance forces the driver to exert more effort to turn the steering wheel, resulting in noticeably heavy or difficult steering.

Worn control arm bushings are unlikely to be the primary cause of steering wheel vibration at 40 mph. Although they can affect overall suspension performance and vehicle stability, they typically do not produce vibrations that are directly felt through the steering wheel.

The most effective way to remove old, dark-colored fluid from a hydraulic power steering system is by flushing it with fresh power steering fluid. Contaminated or discolored fluid often indicates the presence of debris or buildup within the system, and a proper flush helps restore clean fluid flow and optimal performance.

Using brake cleaner, carburetor cleaner, or harsh solvents is not recommended, as these chemicals can damage seals and internal components of the power steering system. Only power steering fluid should be used for cleaning and maintenance to ensure system integrity.

A shock absorber is a hydraulic device designed to manage suspension movement. It cushions the impact from bumps and uneven road surfaces while helping maintain consistent tire contact with the road for better stability and control.

Technician A is correct: A faulty vehicle speed sensor signal can cause the Variable Effort Steering (VES) system to malfunction. The VES controller relies on this signal to determine vehicle speed and adjust hydraulic pressure accordingly. If the signal is inaccurate or missing, the system may fail to reduce hydraulic pressure at higher speeds, resulting in poor steering response.

Technician B is also correct: When the VES system fails to reduce hydraulic pressure at highway speeds, the steering may feel loose or imprecise because the system doesn’t provide the expected steering assistance.

Therefore, both technicians are correct in their assessments.

Technician A is correct in stating that Steering Axis Inclination (SAI) can be indirectly influenced by adjusting the caster angle. The caster angle—defined by the tilt of the steering axis when viewed from the side—can alter the steering geometry and have an effect on SAI.

Technician B is also correct in noting that camber is part of the Included Angle. The Included Angle is the sum of the SAI and the camber angle. Since camber refers to the tilt of the wheel from vertical when viewed from the front or rear, any camber adjustment directly changes the Included Angle.

Therefore, both technicians are correct in their explanations.

Front-wheel setback refers to the difference in distance between the centerline of the front wheels and the centerline of the rear wheels on either side of the vehicle. While a small amount of setback is often acceptable and may fall within the manufacturer’s specifications, a significant discrepancy can lead to alignment problems and poor handling.

Technician A’s statement—that setback is intentionally built in to account for crowned roads—is inaccurate. Although minor design allowances may exist for road crowning, they do not justify a substantial setback difference.

Technician B is correct in noting that excessive front-wheel setback can cause the vehicle to drift toward the side with the greater setback. This is because the wheel positioned further back alters the vehicle’s tracking and steering geometry, leading to a noticeable pull in that direction.

Technician A is correct in stating that a faulty jounce bumper can cause a vehicle to fail the jounce test. The jounce bumper is designed to cushion the suspension when it reaches full compression. If it’s damaged or missing, the suspension may bottom out during the test, leading to a failure.

Technician B is also correct. On an SLA (Short Long Arm) suspension, the jounce bumper is typically mounted on the lower control arm. To replace it, the lower ball joint—which connects the control arm to the steering knuckle—must be removed to access and remove the bumper properly.

The correct indication of excessive play between the rack piston and sector in an integral power steering gear is “lost motion within the steering gear.” This condition results in delayed or unresponsive steering input, giving the driver a feeling of looseness or hesitation when turning the wheel. While other issues—like hard steering when cold or hot, or steering wheel vibration—may point to separate steering system problems, they are not direct symptoms of excessive play between the rack piston and sector.

Technician A is correct in stating that steering axis inclination (SAI) is a factory-set angle and is not adjustable. SAI is the angle formed between the steering axis and a vertical line when viewed from the front of the vehicle. It is built into the design of the suspension and steering system, and although it cannot be adjusted, it can be altered by damage or wear to components such as ball joints or strut assemblies.

Technician B is also correct. Both SAI and caster angle influence the steering wheel’s ability to return to center. Caster, which is the angle between the steering axis and a vertical line viewed from the side, contributes significantly to the self-centering action. A more positive caster angle enhances this effect, improving straight-line stability and steering wheel return after a turn.

The steering rack mounting bushings are the least likely cause of a squeaking or clunking noise when driving over small bumps in a light truck equipped with a solid rear axle and coil-spring suspension. Since the steering rack is located at the front of the vehicle and is part of the steering system, it is unlikely to contribute to noise coming from the rear of the truck.

In contrast, the leading and trailing control arm bushings, as well as the track bar bushings, are all components of the rear suspension. These parts help stabilize and control axle movement. If any of these bushings are worn or deteriorated, they can produce noise and contribute to a loose or unstable ride, especially over bumps.

Technician A is correct in stating that many torsion bars can be adjusted to change the vehicle’s ride height; however, this capability depends on the specific suspension design of the vehicle. Technician B is also correct that some torsion bars are labeled for the left or right side and should be reinstalled in their original position. That said, not all torsion bars are marked, so this may not apply to every application.

Technician A is correct in emphasizing the importance of consulting online service information for the proper airbag disabling procedure when working on the steering column. Since the airbag system is a critical safety feature, improper handling can lead to accidental deployment and serious injury. Because procedures can vary by vehicle make and model, following the manufacturer’s specific guidelines is essential for safe and effective service.

Both Technician A and Technician B are correct. Loose tie rod ends can lead to a loose or vague steering feel, causing the vehicle to wander and requiring constant steering corrections to stay in its lane. A common method to check for worn or loose tie rod ends is by rocking the tire back and forth at the three and nine o’clock positions. If noticeable play or movement is observed during this test, it often indicates that the tie rod ends are worn and may need replacement.

Toe-Out-On-Turns (TOOT) is an angle built into the steering arms that causes the front wheels to toe outward during a turn. This design helps the tires follow their proper turning radius and prevents tire squeal. If tire squealing occurs while cornering, it may be a sign that the TOOT angle is incorrect or that there’s an issue with the steering geometry, and it should be inspected.

Technician A is correct in stating that the leaf spring shackle swivels to allow the spring to flex and flatten as the vehicle moves over bumps. This movement is essential for proper suspension articulation and ride comfort.

Technician B suggests that a single crack in the longest blade of a multi-leaf spring may be acceptable if ride height is unaffected and the other blades are intact. However, any crack in a leaf spring—especially in the main leaf—compromises the suspension’s structural integrity and can increase the risk of failure. For safety and reliability, it is generally best practice to replace any leaf spring that shows signs of cracking or damage.

Belt deflection refers to how much the belt moves or sags when pressure is applied. Proper belt tension is essential for the power steering pump to operate efficiently.

For every foot (30.5 cm) of free span, the power steering pump belt should deflect about 0.5 inch (12.7 mm) under pressure. This amount of deflection indicates the belt is correctly tensioned and helps ensure reliable performance of the system.

Technician A is correct in explaining camber as the inward or outward tilt of the wheels relative to vertical. When the top of the tire tilts inward, it’s called negative camber; when it tilts outward, it’s positive camber. Camber affects how the tire contacts the road: negative camber places more load on the inner edge of the tire, leading to inside-edge wear, while positive camber shifts the load to the outer edge, causing outside-edge wear.

Technician B is also correct in describing rebound as the suspension’s upward movement after compression. In an SLA (Short Long Arm) suspension, the upper control arm pivots on a ball joint. During rebound, this movement can introduce a slight increase in negative camber. Although this change is usually minimal, over time it can contribute to uneven tire wear.

Toe-in refers to the angle formed when the front edges of a pair of tires point inward toward the vehicle’s centerline. Positive toe means the front of the tires are closer together than the rear, while negative toe means they’re farther apart.

In this scenario, the right rear wheel has a toe-in that is 1.5 degrees more than the specification, meaning the front of that tire is angled 1.5 degrees closer to the centerline compared to the rear. Technician B is correct in identifying this as a positive toe deviation, as it reflects an inward (toe-in) orientation beyond the specified range.

Caster is the angle between the steering axis and a vertical line when viewed from the side of the vehicle. A positive caster means the steering axis tilts toward the rear of the vehicle, while a negative caster tilts toward the front.

Caster is crucial for steering stability and self-centering. It helps the wheels stay aligned with the direction of travel during turns and assists the steering wheel in returning to center afterward.

However, if the caster angle is excessively positive, it can cause the steering wheel to snap back to center too aggressively, making the vehicle harder to control—especially at higher speeds.

Technician A is correct in stating that a misaligned steering column input shaft can cause noise. This shaft links the steering wheel to the steering gearbox or rack-and-pinion system, and if it’s not properly aligned, it can place uneven stress on the components, leading to noise and potential damage.

Technician B is also correct that low lubricant levels in a linkage-assist power steering system can result in noise during steering. These systems rely on properly lubricated linkages and gears for smooth operation. When lubricant is low, increased friction can cause noise and may eventually damage the components.

• Excessive negative caster can lead to unstable steering and cause the vehicle to wander, especially on rough or uneven roads.

• Toe describes the angle at which the tires point inward or outward when viewed from above. Incorrect front-toe alignment can cause the vehicle to pull or drift to one side, particularly when driving over bumps or irregular surfaces.

• Bump steer happens when changes in suspension travel—such as hitting bumps—cause the wheels to steer unintentionally. Worn or damaged front or rear suspension components can contribute to this condition, resulting in wandering on bumpy roads.

Both Technician A and Technician B are correct. Torsion bar suspension systems allow for ride height adjustments by turning the torsion bar. Technician A is right in stating that this adjustment can be used to correct ride height. However, as Technician B points out, it is essential to measure the vehicle’s current ride height before making any changes. Measuring before and after adjustments ensures accuracy and helps maintain ride height within the manufacturer’s specifications.

The steering wheel sensor is usually positioned at the base of the steering column, close to the steering wheel. It monitors the position and movement of the steering wheel using technologies such as optical sensors, magnetic sensors, or potentiometers.

The data from this sensor is sent to the vehicle’s electronic control module (ECM), which interprets the driver’s steering input and helps control systems like electric power steering. Precise and dependable readings from the steering wheel sensor are crucial for proper steering function and overall vehicle safety.

Jounce bumpers, also known as bump stops, are designed to absorb impact and cushion the suspension system, helping protect both passengers and suspension components from harsh jolts. They are installed on both the front and rear suspension systems.

Technician A is correct that loose power steering rack bushings can contribute to vehicle wander. In addition, other components—such as worn tie rod ends, ball joints, or control arm bushings—can also cause this issue.

Technician B is also correct in stating that worn rack bushings can lead to toe changes. These bushings secure the steering rack and limit its movement during steering. If they are worn, the rack may shift under load, affecting wheel alignment and altering the toe angle.

If a vehicle with variable-assist power steering feels loose or unresponsive at highway speeds, it may indicate a malfunction within the system. At higher speeds, the system is designed to reduce steering assist, providing a firmer and more stable feel. A failure to do so could be due to a faulty pressure control valve, worn steering gear, or other power steering components.

Variable-assist power steering is designed to adjust the level of steering assistance based on vehicle speed—offering greater assistance at low speeds for easier maneuvering, and reducing assistance at high speeds for improved control and stability.

Technician A is correct in stating that the cradle can be measured from multiple reference points to determine if it is bent. Since the cradle consists of several interconnected components, a distortion in any part can impact the alignment of the entire assembly.

Technician B is also correct that some cradles feature an alignment hole that must line up with a corresponding hole in the chassis. This alignment point helps ensure that the cradle is correctly positioned relative to the chassis during installation or inspection.

Tire pressure should be checked and adjusted when the tires are cold—either after the vehicle has been parked for at least three hours or driven less than one mile. This is important because tire pressure rises as the tires heat up, and checking them while warm can lead to inaccurate readings, resulting in improper inflation.

Over-inflated tires tend to wear more quickly in the center of the tread, while under-inflated tires wear more along the edges. Under-inflation can also lead to tire or wheel damage, as the added flexing generates heat and increases the risk of tire failure.

Technician A is correct in stating that a light film of oil on the shaft of a shock absorber is normal. This thin layer results from internal lubrication and does not indicate a problem.

However, Technician B is incorrect. Even a small drip of oil seeping from the shock absorber body signals a leak. Shock absorbers are sealed units, and any visible fluid leakage suggests internal damage or seal failure. This can impair the shock’s ability to dampen suspension movement and should be inspected and repaired or replaced promptly.

If a technician is unbolting a sensor with the ignition on and the engine off while reviewing scan tool data for correct operation, the sensor being tested is the G-sensor.
The G-sensor, also known as the accelerometer or gravity sensor, measures the vehicle’s acceleration and deceleration forces in various directions. It provides important information to the electronically controlled suspension system to adjust the suspension settings based on the vehicle’s dynamic conditions. By reviewing the scan tool data while unbolting the sensor, the technician is likely checking if the G-sensor is functioning correctly.

Technician A is correct because bent suspension components can result in incorrect ride height. A bent part may not properly support the vehicle’s weight, leading to uneven or incorrect height measurements.

Technician B is also correct, as some ride height specifications require the vehicle to have a full fuel tank. Fuel adds weight to the vehicle, and measuring ride height with an empty tank can produce inaccurate results. A full tank ensures consistency and accuracy when comparing to manufacturer specifications.

To safely unload the ball joints on a front suspension with the coil spring located between the lower control arm and the frame, a safety stand should be placed under the lower control arm. This ensures the vehicle’s weight is properly supported and keeps the suspension stable during the procedure. Using a safety stand in this position helps prevent accidents or damage by maintaining support while working on the ball joints.

Holding the steering wheel against the stops for more than five seconds can dangerously increase pressure in the power steering system. This excessive pressure may rupture hoses or damage components like the power steering pump or steering gear.

Power steering systems rely on hydraulic fluid to assist with steering. When the wheel is turned to its limit and held there, fluid flow is restricted, causing pressure to build rapidly. Sustained pressure buildup puts stress on hoses and other system parts, increasing the risk of failure.

To prevent damage, avoid holding the wheel at full lock for more than five seconds. If it must be held briefly, release it momentarily every few seconds to allow the pressure to drop.

The stabilizer bar—also called the sway bar or anti-roll bar—is a key suspension component that helps control body roll by linking the left and right sides of the suspension. During cornering, it transfers force from one side of the vehicle to the other, reducing body lean and improving stability.

If a stabilizer bar link is broken or damaged, the bar cannot function effectively. This leads to increased body roll during turns, as the suspension can no longer properly resist lateral movement, compromising handling and comfort.

Loose inner tie rod ends can cause vehicle shimmy and feathered tire wear. These components connect the steering rack to the steering knuckle and play a crucial role in maintaining proper alignment and steering response. Located within the steering system, inner tie rods are not visible without removing the wheel.

Each inner tie rod end is protected by a rubber boot that keeps out dirt and debris. If the boot is torn or damaged, contaminants can enter and accelerate wear, leading to premature failure.

On rack-and-pinion steering systems, toe adjustments are made by rotating the inner tie rod ends. Toe refers to the angle of the tires in relation to each other when viewed from above. Proper toe alignment is essential for even tire wear and responsive handling. Adjusting toe typically requires a special tool, which is commonly available at auto parts stores.

When a vehicle’s ride height is too low, it can lead to pulling to one side due to changes in suspension geometry. Uneven ride height affects wheel alignment, causing the wheels on one side to be angled differently than those on the other, which disrupts directional stability.

Ride height also directly influences front camber. Camber is the tilt of the wheels relative to the vertical axis when viewed from the front or rear. A lowered ride height typically increases negative camber, causing the tops of the wheels to tilt inward. In contrast, an elevated ride height can create positive camber, with the tops of the wheels tilting outward. Both conditions can affect handling and tire wear.