PIT3098D

File in Section:
Service Bulletin
Bulletin No.:
Date:
PIT3098D
September, 2012
PRELIMINARY INFORMATION
Subject:
Vehicle Body Tilt Or Lean Diagnostic Information
Models:
1999 - 2006 Cadillac Escalade Models
1999 - 2006 Chevrolet Avalanche, Suburban, Tahoe
2007 - 2013 Chevrolet Suburban HD
1999 - 2007 Chevrolet Silverado Classic
2007 - 2013 Chevrolet Silverado HD
1999 - 2007 GMC Sierra Classic
2007 - 2013 GMC Sierra HD
1999 - 2006 GMC Yukon, Yukon XL, Yukon Denali, Yukon Denali XL
2007 - 2013 GMC Yukon XL HD
With Torsion Bars
This PI was superseded to update warranty information, model and model years. Please
discard PIT3098C.
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
This procedure should be followed to diagnose and correct customer complaints of vehicle leaning left or right. The
same steps are followed whether the lean appears in the front, rear, or both ends of the vehicle. Generally the
vehicle's stance can be adjusted with the torsion bar adjuster bolts. In certain cases, however, other changes may be
needed.
Recommendation/Instructions:
Measure fender wheel-opening heights, front and rear, to quantify vehicle lean. Fender wheel-opening heights are
related to, but distinct from, trim height (a.k.a. Z and D height). The front wheel-opening height is known as P height,
and the rear wheel-opening height is known as R height. The P and R heights are not set at the factory, nor is a
specification given for them. However, they are the most direct and repeatable measurement of what a customer
would perceive as a leaning condition.
Perform the following before measuring the fender wheel-opening heights:
• Make sure the vehicle is on a level surface, such as an alignment rack.
• Remove the alignment rack floating pins.
• Set the tire pressures to the pressure shown on the certification label. Refer to Label - Vehicle Certification in
General Information.
• Set the tire pressures to the pressure shown on the certification label. Refer to Label - Vehicle Certification in
General Information.
• To ensure proper weight distribution make sure the rear storage compartment is empty.
• Close the doors and hood.
P Height and R Height Measurements:
P height and R height are measured the same way. They are the distance from the ground to the highest point on
their respective wheel-opening, going through the center of their respective wheel.
If the difference left to right, P and or R height is 1/2 inch (12 mm) or less no repairs are suggested as the vehicle is
within specification. If the difference left to right exceeds 1/2 inch (12 mm) follow 1 of the 3 diagnostics below.
1. If P height is more than 1/2 inch (12 mm) different left to right, and R height is more than 1/2 inch (12 mm)
different from left to right.
1.1. Check Z height and D height. See Trim Height Inspection Procedure.
1.2. If Z height is out of spec and D height delta is greater than 1/2 (12 mm), adjust Z height until it is within spec
and P and R height deltas are less than 1/2 inch (12 mm).
1.3. If Z height is within spec but D height delta is greater than 1/2 inch (12 mm), adjust Z height to reduce P
and R height deltas to less than 1/2 inch (12mm), staying within the Z height tolerance. If this is not
possible, check front eye of rear leaf spring for matching color-coded tape or paint. Both sides should be
the same color. If not, switch springs side to side. If so, replace leaf spring on lower side only.
1.4. Recheck Z, D, P, and R heights.
1.5. If Z height is out of spec but D height delta is less than 1/2 inch (12 mm), adjust Z height until it is within
spec and P and R height deltas are less than 1/2 inch (12 mm). If this is not possible, shim the front fenders
and box as needed.
1.6. If Z height is within spec and D height delta is less than 1/2 inch (12 mm), adjust Z height, within tolerance,
until P and R height deltas are less than 1/2 inch (12 mm). If this is not possible, shim body and/or pick-up
box until P and R height deltas less than 1/2 inch (12 mm).
2. If P height is within 1/2 inch (12 mm) left to right, and R height is more than 1/2 inch (12 mm) different from left to
right.
2.1. Check Z height and D height. See Trim Height Inspection Procedure.
2.2. If Z height is out of spec and D height delta is greater than 1/2 inch (12 mm), adjust Z height until it is within
spec and P and R height deltas are less than 1/2 inch (12 mm).
2.3. If Z height is within spec but D height delta is greater than 1/2 inch (12 mm), adjust Z height to reduce P
and R height deltas to less than 1/2 inch (12 mm), staying within the Z height tolerance. If this is not
possible, check front eye of rear leaf spring for matching color-coded tape or paint. Both sides should be
the same color. If not, switch springs side to side. If so, replace leaf spring on lower side only.
2.4. Recheck Z, D, P, and R heights.
2.5. If Z height is within spec and D height delta is less than 1/2 inch (12 mm), shim body and/or pick-up box
until P and R heights are within 1/2 inch (12 mm) left to right.
3. If P height is more than 1/2 inch (12 mm) different from left to right, and R height is within 1/2 inch (12 mm) left to
right.
3.1. Check Z height and D height. See Trim Height Inspection Procedure.
3.2. If Z height is out of spec and D height delta is greater than 1/2 inch (12 mm), adjust Z height to spec.
Recheck P, R, and D heights.
3.3. If Z height is within spec and D height delta is less than 1/2 inch (12 mm), adjust Z height, staying within
tolerance, until P height delta is less than 1/2 inch (12 mm) and R height delta is less than 1/2 inch (12
mm). If this is not possible, add fender shims as necessary to make P and R height deltas less than 1/2
inch (12 mm).
3.4. If Z height is out of spec and D height delta is less than 1/2 inch (12 mm), adjust Z height until within spec
and P and R height deltas are less than 1/2 inch (12 mm). If this isn't possible, check D height with Z height
in spec. If D height delta is greater than 1/2 inch (12 mm), then check front eye of rear leaf spring for
matching color-coded tape or paint. Both sides should be the same color. If not, switch springs side to side.
If so, replace leaf spring on lower side only.
3.5. Recheck Z, D, P, and R heights.
3.6. If Z height is within spec and D height delta is greater than 1/2 inch (12 mm), shim front fenders to get P
height delta less than 1/2 inch (12 mm).
4. After all adjustments are done, perform a front-end alignment and check headlight aim.
Warranty Information:
The correction for this concern may be one of several repairs described in the diagnostic tips above.
For vehicles repaired under warranty use:
ADDITIONAL SI KEYWORDS:
sag
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is
resolved without completing every step, the remaining steps do not need to be performed.