PIP5293

Bulletin No.: PIP5293
Date: May-2015
Subject:
Transmission Noise On Engine Start-Up
Models:
2015 Cadillac Escalade, Escalade ESV
2015 Chevrolet Silverado
2015 GMC Sierra, Yukon, Yukon XL
Equipped with 8L90 Automatic Transmission (RPOs M5U)
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern
Some customers may comment on a noise from the transmission when the engine starts.
This noise may be described as a clunk, there may also be a bump sensation at the time of the noise.
The propeller shaft may also show a slight rotation when this noise occurs
Recommendation/Instructions
This condition may be induced by shutting off the engine and quickly restarting the engine.
During a rapid engine restart, the TCM does not have adequate time to power-down and the 1-2-7-8-R and 1-2-3-4-5-R clutches will apply at maximum line
pressure causing the condition.
This is a normal condition if the TCM is not allowed to power-down.
A TCM power-down requires the transmission be placed into Park, ignition off, open and close the driver door, wait two minutes.
If the condition can be duplicated after a complete TCM power-down please contact TAC for further direction.
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.
GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may
occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools,
safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that
your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.
WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION
1