A/T - THM 700-R4 New Harness/Solenoid Assembly
88chevy27Number: 88-335-7A
Section: 7A
Date: SEPT., 1988
Subject: SERVICE MANUAL UPDATE: NEW SOLENOID ASSEMBLY AND WIRING HARNESS
Model and Year: 1988 C, K, R, V, S, T, G SERIES TRUCKS WITH THM 700-R4
TO: ALL CHEVROLET DEALERS
This bulletin covers the introduction of a new Solenoid Assembly and Wiring Harness (Type 18) and new Control Valve Assembly for some 1988 THM 700-R4 models (refer to models listed below).
Transmission Models: MAM, MDM, MFM, MKM, MLM, MPM, MRM MWM, MXM, MZM, THM, TJM, TKM, TLM TUM, TXM
The new control valve assembly uses a plug in place of the 4-3 pulse switch. The function of the 4-3 pulse switch, to momentarily release the [1][2]torque converter clutch during a 4-3 downshift, was programmed into the ECM for the 1988 model year. These models had previously used a Type 15 Solenoid Assembly.
FIGURE 1 - THM 700-R4 TRANSMISSION IDENTIFICATION INFORMATION:
FIGURE 2 - THM 700-R4 WIRING DIAGRAM:
DATE OF PRODUCTION CHANGE: (Figure 1)
On April 20, 1988 (Julian Date 111), the 1988 THM 700-R4, THM and TLM models were built with the new Type 18 Solenoid Assembly and Wiring Harness.
Beginning May 9, 1988 (Julian Date 130), the remaining 1988 THM 700-R4 models listed above were built using the new Type 18 Solenoid Assembly.
SERVICE NOTES:
Any 1988 THM 700-R4 transmission models built with the Type 18 Solenoid Assembly, refer to models and Julian Dates listed above, must be serviced with the Type 18 Solenoid Assembly and Wiring Harness Complete listed under "Service Parts Information".
Any 1988 THM 700-R4 transmission model built with a Type 15 Solenoid Assembly may be serviced with the new Type 18 assembly; however, there will be no wire connection for the 4-3 pulse switch. The 4-3 pulse switch, which can be left installed, will then function as a plug.
SERVICE PARTS INFORMATION:
Part No. Description
10478100 Type 18 Solenoid Assembly - Complete
8654415 Type 15 Solenoid Assembly - Complete
Parts are currently available from GMSPO.
SERVICE MANUAL REFERENCE:
Please update the 1988 THM 700-R4 Hydraulic Diagnosis section of your service manual accordingly.