SLIP/BUMP DURING 3-2 DOWNSHIFT VALVE AND PUMP P/N

TRANSMISSION APPLICATIONS: SUBJECT: ------------------------- ------- 1988 THM 125C (MD9) SLIP BUMP DURING 3-2 DOWNSHIFT

TRANSMISSION MODELS: VEHICLE APPLICATIONS: ------------------- -------------------- BHC, BJC, KDC 1988 N CAR WITH 2.3 L OR 3.0L ENGINE

BULLETIN COVERS:

A Slip Bump condition during a part throttle 3-2 downshift (Forced Throttle) maneuver, may be caused by excess material left in the 3-2 control valve bore during machining of the Control Valve and Oil Pump Assembly.

DATE OF PRODUCTION CHANGE: (Figure 1) ------------------------- November 11, 1987 (Julian Date 315) corrected control valve assemblies went into production.

SERVICE ACTION:

To repair this condition on a 1988 N Car with a 2.3L or 3.0L Engine and equipped with a THM 125C with a listed Julian Date lower than 315 install a new Control Valve and Oil Pump Assembly.

SERVICE PARTS INFORMATION: (Refer to Figure 2) ------------------------- When ordering a new Control Valve and Oil Pump Assembly refer to the following part list:

Part No. Package Description Models ------- ------------------- ------ 8664791 Control Valve and Oil Pump Assembly BHC 8664791 Control Valve and Oil Pump Assembly BJC 8664794 Control Valve and Oil Pump Assembly KDC

SERVICE MANUAL REFERENCE:

When servicing a 125C transaxle for this condition replace the Control Valve and Oil Pump Assembly. Refer to the procedure given in 125/125C Unit Repair Section of your Service Manual.

SERVICE NOTES:

For warranty purposes, use Labour Operation K6570.

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.