Component Tests and General Diagnostics

NOTE: Codes identifying the front torsion bar and rear spring options and springs are printed on the Safety Standard Certification Label. Replace springs in pairs if one is found to be damaged or worn. If a spring should require replacement because it is damaged, worn or due to a leaning condition, replace only with the same part specified on the label. In rare instances, the spring codes will not reflect the springs as installed due to a district special order (DSO) option or assembly plant substitution. If a DSO option number is shown on the certification label, the District Office can establish whether springs are affected. If the factory-installed springs do not agree with the code printed on the Safety Standard Certification Label (right and left coil or leaf spring part numbers should match [Note the front torsion bars have different base part numbers on the left and right sides.]), replace the damaged or worn spring with a new spring of the same part number as the damaged or worn spring. It will not be necessary to replace the matching, non-worn or undamaged spring.

Side-to-side vehicle lean should be verified by measuring the fender lip-to-ground dimension before beginning diagnosis and repairs. Normal acceptable limits are:
^ Maximum of 16 mm (5/8 inch) variance between left and right front wheel lips to ground.
^ Maximum of 19 mm (3/4 inch) variance between left and right rear wheel lips to ground.

1. Place the vehicle on a flat, smooth surface.
2. Inspect the vehicle for any heavy add-one that may cause excessive weight on any corner of the vehicle.
^ In cases where the excess weight is a snow plow, a rear tailgate lift, etc., the vehicle must be diagnosed with the equipment in place.
^ Measure corner weights if necessary.
^ Vehicle fuel tanks should be full and the vehicle empty of cargo such as tools, equipment or debris in the pickup box or rear body section.
^ Vehicle must be sitting on the wheels and tires and not a hoist, jack or jackstands.

3. Check all wheels and tires:
^ Wheels must be the same size and design, right and left side on each axle.
^ Wheels size and design, tire size and tire design should be as indicated on the Vehicle Certification Label.
^ Check air pressure and inflate.

4. Check the front and rear suspension. (Note the front torsion bars have different base part numbers on the left and right sides.) Make sure the same spring is on the left/right rear. Verify that the left and right torsion bars are installed on the correct side. The rear springs have the part number stamped on the bottom just behind the U-bolt attachment.
5. Jounce the vehicle's front and rear suspension to normalize the vehicle static ride height.





6. Measure the height of the right and left fender lip openings for both front (dimension A) and rear (dimension B).
7. Calculate the side-to-side differences for each dimension. If these differences are greater than 16 mm (5/8 inch) between left or right front and/or 19 mm (3/4 inch) between left and right rear adjust as necessary.