A/T - Intermittent Harsh Shifting
Group: TRANSAXLENumber: 93-40-007
Date: JUNE, 1993
Model: SCOUPE
Subject:
AUTOMATIC TRANSAXLE SHIFTS HARD (REVISION)
THIS TECHNICAL SERVICE BULLETIN SUPERSEDES TSB # 92-40-002
Some 1991, 1992 Scoupes with automatic transaxles may experience intermittent harsh shifting during first to second upshift or second to first downshift at low vehicle speeds. Customers may describe this feeling as a revving up in neutral and then a harsh bang into gear or a late shift. This normally occurs when creeping along at low speeds (8-15 mph) such as in heavy traffic or when coming to a stop. This condition could be intermittent so you may not be able to duplicate the symptom during a road test. If customer complaints match those above, perform the test procedures given in this TSB.
This condition is generally caused when pulse generator "B" loses continuity intermittently due to a wiring or connector problem. This may result in transaxle fault code of 33, 13 and/or 53, but will not always set a code.
Excessive strain on the transaxle control harness from the engine movement and the restriction of a nearby tie wrap may cause the following conditions:
1. Distortion of pins inside the connector T01.
2. Pins pulled out of connector T01.
3. Internal breakage of the wires in the transaxle control harness.
The cause is rarely the result of a bad pulse generator.
SERVICE PROCEDURE
NOTE:
Check and adjust transaxle fluid level prior to road testing if necessary.
Connector inspection/repair
1. Cut the tie wrap shown in Fig. 1 to relieve the tension on the pulse generator "B" wires.
2. Separate the male and female halves of the connector T01.
3. Inspect each female pin for distortion. Reshape by inserting a small flat screwdriver between the pins and bending them gently by rocking the screwdriver side to side (Figure 3).
4. Bend each male pin gently away from the plastic separator with a flat screwdriver.
Wiring/connector continuity check
5. Perform a continuity check of the transaxle control harness. You can perform either a "wiggle test" or energize the pulse generators and use the MUT Energizing the pulse generators and using the MUT is a preferred procedure as it checks the entire circuit without disturbing any of the connections.
Wiggle Test
Disconnect the harness from the Transaxle Control Module (TCM) and from the pulse generators at connector T01. Connect an ohmmeter between the connectors as shown in Fig. 4. Shake and pull on the wires and connectors, watching for the resistance to go to infinity (indicating an open circuit). Correct the wiring problem.
MUT Test
^ Turn the ignition switch to "ON" and connect the MUT Select the "ELC-4AT" system and display both pulse generating readings, PG-A and PG-B, on the MUT screen.
^ Remove the pulse generators from the transmission (leave them plugged in) and hold the body of the soldering gun (not a soldering iron) or electric pencil next to the pulse generator.
CAUTION:
Make sure the soldering gun or electric pencil end is clear of any wires or lines!
^ Turn the soldering gun on and watch the MUT reading for that pulse generator. If there is continuity on that circuit the MUT will display an RPM reading for that pulse generator.
^ Shake and pull on the wires and connectors, watching for the rpm reading to go to zero (0) (indicating an open circuit). Do the same for pulse generator "A". Correct any wiring problems.
6. Reconnect the male and female connectors at T01 and T10-2.
7. Erase any previously stored transmission codes.
8. Road test the vehicle.
WARRANTY INFORMATION