ERRATIC SHIFT, 2ND/3RD STARTS NO TCC OR SLIPPING CONDITION
SUBJECT: ERRATIC SHIFT, 2ND/3RD STARTS, NO TCC OR SLIPPING CONDITION - PLASTIC SHOT LODGED IN SPACER PLATE
MODELS/YEARS: ALL 1992 WITH 4T60 AND 4T60E
CONDITION: Some vehicles equipped with a 1992 HYDRA-MATIC 4T60 (RPO ME9) or 1992 HYDRA- MATIC 4T60-E (RPO M13) transaxle built on or before April 1, 1992 (Julian Date 092) may exhibit erratic shifts, 2nd gear starts, 3rd gear starts, no TCC, or a slipping condition.
CAUSE: The above condition may be caused by plastic shot lodged in a spacer plate orifice causing a restriction to that passage. The condition is dependent on location and degree of shot entrapment. The transaxle may have been assembled with shot stuck between the casting walls or hub surface of the channel plate and eventually forced into the spacer plate. The shot is originally yellow or white in color but may become translucent when exposed to normal transaxle operating temperatures. The plastic shot may also become pliable and conform to the diameter of the orifice. These two factors make the condition very hard to identify, especially when inspecting the smaller orifice in the spacer plate.
CORRECTION: Begin with the "Quick Check Procedure" ("Automatic Transaxle Diagnosis" section of the 1992 Service Manual) which provides a general outline of how to properly diagnose a HYDRA-MATIC 4T60/4T60-E transaxle. This procedure will aid the technician in choosing the proper path to diagnose the symptom by describing the basic checks and then referencing the location of the specific diagnostic checks. This will ensure the vehicle has been properly diagnosed and no unnecessary repairs are per- formed.
If it is suspected the transaxle contains this concern, it is essential that the channel plate and spacer plate be inspected 1 00 percent. This can be accomplished by the following procedure: NOTE: Make certain the work area is adequate and CLEAN for the layout and inspection of components.
Spacer Plate Assembly Inspection
o Remove spacer plate assembly from transaxle (refer to Section 7A of the appropriate 1992 service manual).
o Carefully remove spacer plate to channel plate gasket, and spacer plate to valve body gasket. Physically probe all spacer plate orifices with a pin or other gage to ensure orifice is not plugged with shot (smaller orifices are more likely to be contaminated and require special attention--refer to the illustration on the back of this bulletin for spacer plate problem areas).
o Thoroughly wash spacer plate assembly and blow dry with an approved compressed air source.
Channel Plate Assembly Inspection
o Remove channel plate assembly from transaxle (refer to Section 7A of the appropriate 1992 service manual.)
o Inspect the entire channel plate assembly, all casting slats and hub surfaces for contamination (refer to the illustration on the back of this bulletin for channel plate problem areas).
o Thoroughly wash channel plate assembly and blow dry with an approved compressed air source (remove manual valve prior to wash to ensure bore is properly cleaned and manual valve moves freely in bore after procedure is completed).
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.
