NOISY TRANSFER CASE IN 4-HIGH PROCEDURE & PARTS UPDATE. GMC Truck S15 Pickup - 4WD 1988

For 1990-2009 cars

# NOISY TRANSFER CASE IN 4-HIGH PROCEDURE & PARTS UPDATE

#### SUBJECT NOISY TRANSFER CASE IN 4-HIGH MODELS: 1988-91 T TRUCKS EQUIPPED WITH NEW PROCESS MODEL 231 TRANSFER CASE

Some 1988-1991 T trucks may experience a noisy transfer case when the truck is in 4-high. The noise is caused by rotation of the chain and gears and is transmitted through the transfer case shift linkage into the body interior. A quieter "T" pattern transfer case chain and softer durometer shift rod grommets have been released to decrease the noise level. The chain can be identified by two blue links while the previous design contained one blue link. The softer grommets are orange or beige while the previous design grommets were white. SERVICE MANUAL REFERENCE Refer to the Unit Repair Section of the appropriate Service Manual for the proper replacement proce- dures.

SERVICE PARTS INFORMATION Quantity Part Number Description Required 15635937 Chain 1 15659238 Shift Rod Grommet 2

Parts are currently available through GMSPO.

WARRANTY INFORMATION

Labor Labor Operation Description Time T7036 Replace Chain and 2.1 hrs. Install Grommet

Parts are currently available through GMSPO.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those 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 a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.