PIT3098F

Bulletin No.: PIT3098F
Published date: 02/13/2018
Preliminary Information
PIT3098F Diagnostic Tips: Vehicle Body Tilt or Lean
Models
Brand:
Model:
Model Years:
VIN:
from
Engine:
to
Transmissions:
Cadillac
Escalade
1999 - 2006
All
All
All
All
Chevrolet
Avalanche
1999 - 2006
All
All
All
All
Chevrolet
Silverado Classic
1999 - 2007
All
All
All
All
Chevrolet
Silverado HD
2007 - 2018
All
All
All
All
Chevrolet
Suburban
1999 - 2006
All
All
All
All
Chevrolet
Suburban HD
2007 - 2013
All
All
All
All
Chevrolet
Suburban 3500HD
2016 - 2018
All
All
All
All
Chevrolet
Tahoe
1999 - 2006
All
All
All
All
GMC
Sierra Classic
1999 - 2007
All
All
All
All
GMC
Sierra HD
2007 - 2018
All
All
All
All
GMC
Yukon Models
1999 - 2006
All
All
All
All
GMC
Yukon XL HD
2007 - 2013
All
All
All
All
With Torsion Bar Front Suspension
Supersession Statement
This PI was superseded to update Model Years. Please discard PIT3098E.
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.
Recommendations / 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.
• Check the fuel level. Add additional weight if necessary to simulate a full tank.
• 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, please
use the appropriate warranty labor operation based on the actual cause and repair.
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.
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