Subjet: TCC APPLIES DURING 1-2 SHIFT (REPLACE CONTROL VALVE BODY ASSEMBLY FOR SERVICE)
Some 1988 Service Replacement Transmission Assemblies (SRTA) may have been built with a bore plug in the TCC valve bore. The 8MHM, 8TAM, 8TBM, and 8TNM models should have the TCC shift valve lineup in this bore instead of the bore plug. If the bore plug is present, TCC will apply during the 1-2 shift.
If the control valve assembly contains a bore plug in place of the TCC shift valve lineup, the control valve assembly must be replaced.
Reference the GMSPO Service Parts Catalog for the correct control valve assembly part number.
Refer to the THM 700-R4 Automatic Transmission Unit Repair Section of the appropriate Service Manual for instructions on replacing the control valve assembly.
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.