Copyright © 1998 General Motors Corp. 6–91
WTEC II ELECTRONIC CONTROLS TROUBLESHOOTING MANUAL
Troubleshooting:
1. Use the Pro-Link
®
diagnostic tool to check the state of the C3 pressure switch.
NOTE: Energizing the solenoids and listening for ball/plunger movement is sometimes useful in
troubleshooting.
2. Check the C3 pressure switch wiring for a short-to-power or a switch stuck closed (refer to
Code 32 XX). If a short is found, isolate and repair; or replace the switch if it is stuck closed.
3. If a fault is not found with the C3 pressure switch or circuitry, connect a pressure gauge to the
C3 pressure tap.
4. Drive the vehicle to make the shift indicated by the code or use the DDR clutch test mode.
Compare actual C3 pressure value with the table of specifications in Appendix B.
5. If C3 is being held on hydraulically (C3 remains pressurized), drain the fluid, remove the control
module, disassemble and clean the control module, checking for damaged valve body gaskets or
stuck and sticky valves (see the transmission Service Manual).
6. If the problem recurs, use spare wire(s) for the C3 pressure switch in the external harness. See
Appendix D for location of spare wires and Appendix E for connector service information.
7. If the problem again recurs, replace the C solenoid (refer to the transmission Service Manual).
8. If the condition persists, replace the ECU. If replacing the ECU corrects the problem, reinstall the
original (bad) ECU to confirm that the problem is in the ECU. If the original ECU now works,
inspect the ECU connectors for any corrosion or damage which may cause an intermittent
condition. If the original problem recurs, reinstall the replacement ECU.
CODE 52 XX — OFFGOING C3 PRESSURE SWITCH TEST DURING SHIFT
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