NEW CONTROL VALVE ASSEMBLY ELIMINATION OF TCC BORE

MODELS: 1982-89 C1, C2, K1, K2, R1, V1, S1 T1, G1, G2, G3, M W/70O R4

BULLETIN COVERS: (Figure No. 1)

Service information for new THM 700-R4/HYDRA-MATIC 4L60 control valve assemblies. The new control valve assembly will no longer have the TCC bore, and now contains a "notch" in the channeling allowing 2nd clutch oil into the TCC circuit (refer to Figure No. 1). The TCC bore, in the past, has housed either the converter clutch throttle valve and sleeve or the converter clutch bore plug. The converter clutch throttle valve was used on models that had non-ECM controlled TCC apply. The converter clutch bore plug was used on models that had ECM controlled TCC apply. Starting with 1989 production, all THM 700-R4/HYDRA-MATIC 4L60 models are ECM controlled TCC apply. Since there are no current production models using the converter clutch throttle valve, the TCC bore is not needed and has been eliminated.

DATE OF PRODUCTION CHANGE: (Figure No. 2) ------------------------- Starting on November 14,1988, Juhan Date 319, all THM 700-R4/HRA-MATIC 4L60 models use the new control valve assemblies.

SERVICE ACTION:

Past THM 700-R4 control valve assemblies that used the converter clutch throttle valve and sleeve (non-ECM controlled TCC apply) will be maintained for service. Service control valve assemblies containing the converter clutch throttle valve and sleeve will continue to be available through GMSPO. The THM 700-R4/HYDRA-MATIC 4L60 control valve assemblies build with the converter clutch bore plug (ECM controlled TCC apply) are serviceable with the new control valve assembly. The new service control valve assembhes (no TCC bore) will supersede the appropriate applications as current service stock is depleted.

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.