NO/SLIPPING TORQUE CONVERTER CLUTCH (SCREENS ADDED TO PWM)
SUBJECT: NO/SLIPPING TORQUE CONVERTER CLUTCH (TCC) WHEN COMMANDED ON SCREENS ADDED TO PWM SOLENOID)
VEHICLES AFFECTED: 1993 "C,E,H,K" MODELS AND "U" VANS
CONDITION: (FIGURE 1) ---------------------
Some 1993 vehicles equipped with a HYDRA-MATIC 4T60-E (RPO M13) transaxle built on or before Julian Date 026 (January 26, 1993) may exhibit no TCC apply, or a slipping TCC condition (possible code 039).
NOTE: The PWM will normally misoperate in either a full apply or a full slip mode. These conditions should not be confused with a TCC chuggle or TCC shudder which is more likely engine performance related.
NOTE: Excessive heat on torque converter may be visible when TCC slipping condition exists.
CAUSE: (FIGURE 2) -----------------
This condition may be due to sediment trapped in the Pulse Width Modulator (PWM) (Illustration #325). Sediment may enter the PWM solenoid from either the control or feed passages and lodge in the flow path around the metering ball causing an undesired exhaust leak.
NOTE: To prevent a customer comeback, careful diagnosis is highly recommended. Do not automatically assume that the condition is caused by the above concern.
Following is a list of other items that may possibly affect Torque Converter Clutch engagement and release. (Refer to the appropriate Service Manual for illustration number reference and component location.)
o Improper operation of PCM.
o Poor connection between PCM to vehicle wiring harness and/or vehicle wiring harness to transaxle pass through connector (35).
o Converter clutch valve (335) stuck.
o Converter clutch regulator valve stuck (332/334).
o Turbine shaft seals (519, 520) damaged or missing.
o Converter clutch blow off checkball (420) seated or damaged.
o Damaged oil pump drive shaft seal (228).
o Missing or mislocated No. 1 checkball (372 (A)).
o TCC solenoid o-ring (316) leaking.
o TCC solenoid (315) inoperative.
CORRECTION: (FIGURES 3 AND 4) -----------------------------
To prevent this from occurring, the spacer plate PWM filter was eliminated (on units built on/after Julian Date 027, January 27, 1993) and screens were added to the control and feed passages on the PWM solenoid. These screens prevent sediment from entering the PWM solenoid.
NOTE: When servicing units built prior to January 27, 1993 (Julian Date 027) it is not necessary to remove the PWM spacer plate filter when replacing the prior PWM with the new PWM.
SERVICE PART INFORMATION:
All 1993 4T60-E transaxle models are affected except for 3CWW and 3CMW.
CURRENT NEW PART NO. PART NO. DESCRIPTION QTY. -------- -------- ----------- ---- 8681523 8683535 Solenoid, Assembly 1 Pulse Width Modulator-PWM
Parts are expected to be available on May 10, 1993.
For vehicles repaired under warranty use:
Labour Time: K6557 for PWM
Solenoid Replace" from the appropriate Labour Time Guide.
SERVICE MANUAL INFORMATION:
Refer to the appropriate Service Manual, Automatic On-Vehicle Service Section 7A for the proper on-vehicle service to remove and replace a PWM solenoid.
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.
