REVISED:TORQUE CONVERT.CLUTCH DIAGNOSIS INFORMATION

Since the start of production, 1982, the THM 125C transmission has had some changes in the auxiliary valve body cover. The changes were implemented to eliminate a light throttle converter clutch shudder condition.

The 1982 auxiliary valve body cover originally had a cast slot in it, (Figure 1) to exhaust oil from the converter clutch regulator valve.

The auxiliary valve body cover was changed mid model year to that of having an orificed cup plug (Figure 2) in place of the cast slot. This orifice then regulated the exhaust from the converter clutch regulator valve.

Approximately May, 1982, the auxiliary valve body cover was changed to omit the orifice in the cup plug (Figure 3). The current production auxiliary valve body cover was changed to a solid cast cover with no cup plug in it (Figure 4).

In servicing any 1982 or 1983 THM 125C transmission, that necessitates the replacement of the auxiliary valve body cover, order service P/N 8637811. This service package will service all past models.

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.