Copyright © 1998 General Motors Corp. 6–89
WTEC II ELECTRONIC CONTROLS TROUBLESHOOTING MANUAL
Troubleshooting:
1. Incorrect fluid level can cause 51 Series codes. Allow the vehicle to idle for 3–4 minutes and check
the transmission fluid level. If level is not correct, add or drain fluid to correct level.
2. If the fluid level is correct, connect a pressure gauge into the pressure tap for the offgoing clutch
indicated by the code (refer to solenoid and clutch chart, Appendix C). Make the shift indicated by
the code or use the Pro-Link
®
diagnostic tool clutch test mode to put the transmission in the
offgoing and oncoming ranges (refer to Appendix B for clutch pressure check information).
3. If the offgoing clutch stays pressurized, drain the fluid, remove the control module, disassemble
the control module and clean it, inspecting for damaged valve body gaskets and stuck or sticky
valves. Inspect the transmission for signs of clutch damage indicating the need to remove and
overhaul the transmission (refer to the transmission Service Manual).
4. If the problem has not been isolated, replace the solenoid for the offgoing clutch (refer to the
transmission Service Manual).
5. If after replacing the solenoid the problem persists, install another ECU. If this corrects the
problem, temporarily reinstall the old ECU to verify the repair.
6. If this does not correct the problem, reinstall the original ECU and check for mechanical problems.
The clutch may be mechanically held (coned, burned and welded, etc.). It may be necessary to
remove the transmission and repair or rebuild as required (see the transmission Service Manual).
CODE 51 XX — OFFGOING RATIO TEST DURING SHIFT (TIE-UP TEST)
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