Copyright © 1998 General Motors Corp.
6–95
W T E C I I E L E C T RO N I C C O N T RO L S T RO U B L E S H O OT I N G M A N UA L
Active Indicator Clearing Procedure:
•
Power down
•
Manual
NOTE:
Before troubleshooting, read Pages 6–17 and 6–18 of Section 6–5. Also, check battery and ECU input
voltages.
NOTE:
Intermittent connections or lack of battery-direct power and ground connections may cause this and
other codes.
NOTE:
Energizing the solenoids and listening for ball/plunger movement is sometimes useful in
troubleshooting.
Troubleshooting:
1. After the transmission is at operating temperature, allow the vehicle to idle on level ground for
3–4 minutes. Check transmission fluid level. If improper fluid level is found, correct as necessary.
Improper fluid level could be the cause of the code (not enough or too much fluid may produce
inadequate clutch pressure).
2. Connect a pressure gauge and check main pressure. If pressure is not adequate, the pump is
possibly worn. See Appendix B for main pressure specifications.
3. If the fluid level is correct, check the turbine and output speed sensors for accurate, steady signals
(not noisy) using the diagnostic tool (check with vehicle stopped and in range to confirm a zero
speed reading from the turbine and output speed sensors). Check the wiring for opens and shorts
(refer to Code 22 XX) and the sensor coils for proper resistance. If problems are found, repair or
replace as necessary. Remove the speed sensor and check for a loose tone wheel.
4. If sensor and wiring resistance is acceptable, connect a pressure gauge(s) to the pressure tap for the
oncoming clutches indicated by the code (refer to solenoid and clutch chart in Appendix C). Make
the shift indicated by the code by operating the vehicle or by using the diagnostic tool’s clutch test
mode.
5. If the clutch pressure does not show on the gauge(s), the control module is probably not
commanding the clutch on. Drain the fluid and remove the control module (see the transmission
Service Manual). Disassemble and clean the control module, inspect for stuck or sticking valves.
6. Internal leakage is indicated by the clutch pressure gauge showing that pressure is being sent to the
clutch but the clutch fails to hold. The fault may be: missing or damaged face seals, burnt clutch,
leaking piston sealrings, or damaged control module gaskets. Drain the fluid, remove the control
module (refer to the transmission Service Manual), and inspect the face seals and control module
gaskets. If the seals and gaskets are satisfactory, replace the solenoid(s) indicated by the code. If
replacing the solenoid does not eliminate the code, remove the transmission and repair as
necessary.
7. If clutch pressures are correct and the clutch appears to be holding, replace the output and turbine
speed sensors (refer to the transmission Service Manual for the proper procedure).
8. If the problem recurs, use the diagnostic tool to check the speed sensor signals for erratic readings.
Possible causes of erratic speed readings are: loose sensors, intermittent contact in the wiring,
vehicle-induced vibrations, or speed sensor wiring that is not a twisted-pair. If necessary, use a
twisted-pair for a new speed sensor circuit — Service Harness Twisted Shielded Pair P/N 29522703
is available for this purpose.
9. 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 54 XX — ONCOMING RATIO TEST (AFTER SHIFT)
