1989 THM 700-R4 TRANSMISSION NEW PRODUCT INFORMATION
MODELS: ALL 1989 C/K, R/V, S/T TRUCKS,G AND M VANS WITH 700-R4 AUTOMATIC TRANSMISSIONS
Bulletin Covers:
New Product Information for all 1989 THM 700-R4 transmissions. Refer to each section of this bulletin for specific product change information.
Date of Production Change: (Figure 1) -------------------------- Beginning with 1989 start of production, all 1989 THM 700-R4 transmissions were built with the product changes explained in this bulletin.
Service Manual Reference:
Changes listed in this bulletin as "Service Manual Update" will note changes made since publication of the 1989 Service Manual and should be noted in your 1989 Service Manual accordingly. Other changes described in this bulletin are included in your 1989 THM 700-R4 Service Manual sections. Be certain to familiarize yourself with these changes to properly service the 1989 THM 700-R4 transmission.
Subject: -------- Input Clutch Assembly With 3-4 Clutch Boost Springs
Change to Assembly Components: (Figure 2) ------------------------------ A new Input Clutch Assembly with 3-4 clutch boost springs (600) was introduced for all 1989 THM 700-R4 models. (This Input Clutch Assembly and 3- 4 clutch boost springs were first used in the 1988 model year on the YDM, YMM, YWM, and YZM models; reference GMC Truck Bulletin 88-T-68). The boost springs aid the release of the 3-4 clutch on downshifts.
Service Action:
When servicing any 1989 THM 700-R4 transmission, the 3-4 clutch boost springs must be used. Improper shift timing can occur if these springs are not installed. When overhauling the 3-4 clutch assembly the 3-4 clutch boost springs should be inserted in place after installation of the 3-4 clutch plates, just prior to installing the 3-4 clutch backing plate and snap ring.
Service Parts Information:
Part No. Description -------- ----------- 8667424 Spring Asm, Boost 3-4 Clutch (600) (5 required)
Parts are currently available from GMSPO.
Service Manual Reference:
This inforrnation is included in your 1989 Service Manual Unit Repair Section. Information that is new for 1989 is noted by an asterisk in the Unit Repair Table of Contents.
Subject: ------- Service Manual Update - 1989 THM 700-R4 Shift Speed and Transmission Pressure Charts
Service Manual Reference:
This information (Figures 3 and 4) has been updated since publication of the 1989 Service Manual. Use this information to update your 1989 THM 700- R4 Automatic Transmission Diagnosis Section.
Subject: ------- Service Manual Update - New THM 700-R4 Electrical Wiring Diagrams
Change to Assembly Components: (Figures 5-7) ------------------------------ Beginning with the 1989 model year, the FMM model THM 700-R4 transmission uses a Type 18 Solenoid Assembly and Wiring Harness (refer to Figure 5). The Type 18 Solenoid Assembly and Wiring Harness was introduced late in the 1988 model year and replaced most Type 15 Solenoid Assembly production (reference GMC Truck Bulletin 89-T-03. The FMM model is the last Type 15 Solenoid Assembly model to change to Type 18 usage. Also for 1989 is the addition of two new solenoid assemblies, Type 19 Solenoid Assembly and Wiring Harness and Type 21 Solenoid Assembly and Wiring Harness (refer to Figures 5 and 7). Both the Type 19 and Type 21 Solenoid Assemblies were introduced on their respective models at 1989 start of production.
Service Parts Information:
Part No. Description -------- ----------- 10478100 Type 18 Solenoid Assembly - Complete
Parts are expected to be available on 12/05/88. Until then normal part orders will not be accepted by GMSPO. Only verifiable emergency VIP orders will be accepted. SPO will make every effort to obtain parts. All parts will be placed on 400 control to waive VIP surcharges. However, the part will be shipped premium transportation at dealer's expense. All other order types will be cancelled as incorrectly ordered while the 400 control is in place.
10478101 Type 19 Solenoid Assembly - Complete
Parts are currently available from GMSPO.
Service Manual Reference:
This information (Figures 5-7) has been updated since publication of the 1989 Service Manual. Use this information to update your 1989 THM 700-R4 Automatic Transmission Diagnosis Section.
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.
