Groan, Clunk Or Bump Noise From Launch Or At Stop - keywords moan pop squawk start

This PI was superceded to update admin. details and wording. Please discard PIP4020C.

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Some customers may comment that their new body style full size pickup makes a groan, clunk or bump noise at parking lots speeds on launch or with light to medium braking. Braking to a complete stop can force the propshaft slip yoke forward into the transfer case while the vehicle rebounds slightly backwards after stopping its momentum and create this noise. This noise may also be due to fuel movement in the fuel tank when not completely full.

Note: This PI does not apply to the Silverado or Sierra classic versions.

Root cause may be the interface between the rear propshaft slip yoke and the transfer case or transmission output shaft splines or fuel movement in the fuel tank. To isolate if the concern is the slip yoke or fuel slosh and not a brake noise the dealer may attempt to duplicate while coasting with the transmission in neutral and braking to a stop. If a groan noise is gone while braking in neutral the noise is slip yoke related. Dealers may lube the slip yoke splines with TransGel (J36850) to help reduce the noise.

If a clunk noise continues after completing the above, the noise has now been isolated to the fuel movement in the tank please make no repair attempts at this time as this noise is considered a operating characteristic.

A Field Product Report should be submitted - refer to the latest version of Corporate Bulletin Number 02-00-89-002F.

If the noise can be isolated to the driveline, lubricating the slip yoke may only be a temporary repair and at this time engineering is investigating this concern. The replacement of any parts may lead to the vehicle returning with the same concern.

NOTE: This PI does not apply to Silverado or Sierra classic versions.

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.