ASE A4 Suspension and SteeringWheel Alignment Diagnosis, Adjustment, and RepairMedium
A vehicle is undergoing a four-wheel alignment. After completing all pre-alignment checks and ensuring the vehicle is level, the technician performs the runout compensation procedure. During this procedure, the alignment machine displays an error message indicating 'Runout Compensation Failed - Excessive Wheel Runout'. What is the most appropriate next step for the technician?
- AProceed with the alignment, as runout compensation is optional.
- BAdjust the vehicle's ride height and reattempt runout compensation.
- CReplace the alignment heads and reattempt runout compensation.
- DInspect the wheel and tire assembly for excessive runout or damage.
Show answer & explanationAnswer & explanation
Correct answer: D. Inspect the wheel and tire assembly for excessive runout or damage.
If runout compensation fails due to 'excessive wheel runout', it indicates a problem with the wheel and/or tire itself, such as a bent rim, damaged tire, or improperly mounted tire. This must be addressed before an accurate alignment can be performed.
Why the other options are wrong
- A. Runout compensation is crucial for accurate alignment; it is not optional.
- B. Ride height affects alignment angles but is not related to wheel runout compensation failure. Adjusting it would not resolve the runout issue.
- C. The error message specifically points to 'excessive wheel runout', not an issue with the alignment heads.
Runout Compensation Failure
Runout compensation (or rolling compensation) is a procedure to eliminate the effects of wheel and adapter imperfections from alignment measurements. Failure often points to issues with the wheel or tire assembly.
- Compensates for wheel/adapter imperfections.
- Essential for accurate alignment readings.
- Failure often means bent wheel, damaged tire, or improper mounting.
Memory trick: Runout failed, 'cause the wheel's not true; check the rim, it's what you must do.