3-4 DOWNSHIFT FLARE SWITCH INFORMATION

Model and Year 1984 THM 700-R4 (YA AND YW)

Beginning March 5, 1984 (Julian Date 065), 1984 models YA and YW THM 700-R4 transmissions were built with a new solenoid and 'O' ring assembly which has a 3 wire harness (P/N 8654129) which is not connected to the 4-3 downshift switch (Figure 1). This is done to reduce a possible 4-3 downshift flare.

The 4-3 downshift switch will remain a part of the control valve body assembly for the remainder of 1984 production for service reasons.

Models built prior to Julian Date 065 were built with a solenoid and 'O' ring assembly that has a 4 wire harness which uses the 4-3 downshift switch (Figure 2).

The 4 wire harness is superseded by the 3 wire harness (P/N 8654129). When servicing the 4 wire harness, replace it with the 3 wire harness and bypass the 4-3 downshift switch as shown in Figure 1.

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.