A/T - THM 700-R4 TCC Applies During 1 to 2 Gear Shift
91chevy18
Number: 88-449-7A
Section: 7A
Date: JULY 1991
Corporate Bulletin No.: 177112R
Subject: TCC APPLIES DURING 1-2 SHIFT
Model and Year: 1988 G2, R1, S1 AND T1 TRUCKS WITH 700-R4 SERVICE REPLACEMENT TRANSMISSION ASSEMBLY
Figure 1 - Control Valve Body:
Bulletin Covers:
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.
Service Information:
If the control valve assembly contains a bore plug in place of the TCC shift valve lineup, the control valve assembly must be replaced.
Service Parts Information:
Reference the GMSPO Service Parts Catalog for the correct control valve assembly part number.
Service Manual Reference:
Refer to the THM 700-R4 Automatic Transmission Unit Repair Section of the appropriate Service Manual for instructions on replacing the control valve assembly.