Steering and vibration complaints are not always the result of improper alignment.
One possible cause is wheel and tire imbalance. Another possibility is tire lead due
to worn or improperly manufactured tires. Lead is the vehicle deviation from a straight
path on a level road without pressure on the steering wheel. Refer to
Radial Tire Lead/Pull Correction
in Tires and Wheels
in order to determine if the vehicle has a tire lead problem.
Before making any adjustment affecting wheel alignment, perform the following
inspections and adjustments in order to ensure correct alignment readings:
| • | Inspect the wheel bearings for backlash and excessive play. Refer to
Wheel Bearings Diagnosis
in Suspension General Diagnosis. |
| • | Inspect the ball joints and tie rod ends for looseness or wear. |
| • | Inspect the control arms and stabilizer shaft for looseness or wear. |
| • | Inspect the steering wheel for excessive drag or poor return due to stiff
or rusted linkage or suspension components. |
| • | Inspect the fuel level. The fuel tank should be full or the vehicle should
have a compensating load added. |
Give consideration to excess loads, such as tool boxes, sample cases, etc. If
normally carried in the vehicle, these items should remain in the vehicle during alignment
adjustments. Give consideration also to the condition of the equipment being used
for the alignment. Follow the equipment manufacturer's instructions.
Satisfactory vehicle operation may occur over a wide range of alignment settings.
However, if the setting exceeds the service allowable specifications, correct the
alignment to the service preferred specifications. Refer to
Wheel Alignment Specifications
.
Important: When performing a wheel alignment service
on a vehicle equipped with the adaptive cruise control (ACC) system, change the Auto
Alignment Learn Status parameter in the distance sensing cruise control (DSCC) module
scan tool Data List to Not Aligned. The Auto Alignment Learn Status parameter in the
DSCC module Data List needs to display Not Aligned to allow the forward looking sensor
(FLS) radar to align automatically after a wheel alignment service. Refer to
Cruise Control Description and Operation
in Cruise Control
for more information on the DSCC module FLS radar alignment.
Perform the following steps in order to measure the front and rear alignment
angles:
- Install the alignment equipment according to the manufacturer's instructions.
- Jounce the front and the rear bumpers 3 times prior to checking the wheel
alignment.
- Measure the alignment angles and record the readings.
Important: When making adjustments to vehicles requiring
a 4-wheel alignment, set the rear wheel alignment angles first to obtain proper front
alignment angles.
- Adjust alignment angles to vehicle specification, if necessary. Refer to
Wheel Alignment Specifications
.
