HARSH/DELAYED UPSHIFTS/700-R4 ADD ATV EXHAUST CHECK BALL

VEHICLES AFFECTED: 1984 Vehicles Equipped with THM 700-R4 Transmissions

Beginning with the 1984 production, the THM 700-R4 transmission is being produced with a T.V. exhaust checkball in the control valve assembly. The purpose of the T.V exhaust checkball is to prevent low or minimum line pressure in the event the T.V. cable should break or become disconnected.

This T.V. exhaust checkball is located beneath the throttle lever and bracket assembly, (Figure #1, #91). It is normally held off of its seat by the throttle lever and bracket assembly. If the T.V. cable should break or become disconnected and T.V. exhaust checkball will seat and cause elevated line pressure, causing harsh and delayed upshifts.

When servicing any THM 700-R4 transmission for harsh and delayed upshifts, install a line pressure gauge to the line pressure tap location to verify elevated line pressures. If line pressure is elevated, inspect the T.V. cable and the throttle lever and bracket assembly for proper connections. Connect and/or replace the cable or bracket assembly as required.

The 1982 and 1983 THM 700-R4 transmission sections will show a T.V. exhaust valve in error. The T.V. exhaust checkball went into production in 1984 and was not used in previous years.

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.