Test 8: A/T Control Problem
- Check specifications code on ABSCM/HU. Code is located between hydraulic line connections. ABSCM/HU may have 3 different codes: C1 (Legacy with A/T and front wheel drive), C3 (all models with A/T and all wheel drive) or C4 (all models with M/T and all wheel drive). If ABSCM/HU is not correct for vehicle, replace with correct ABSCM/HU. If ABSCM/HU is correct for vehicle, go to next step.
- Turn ignition off. Disconnect Transmission Control Module (TCM) connectors. Disconnect ABSCM/HU connector. Measure resistance between ground and ABSCM/HU connector terminal No. 3. See Figure
. If resistance is more than one megohm, go to next step. If resistance is less than one megohm, repair wiring harness between TCM and ABSCM/HU.
- Measure voltage between ground and ABSCM/HU connector terminal No. 3. See Figure
. If voltage is less than one volt, go to next step. If voltage is more than one volt, repair wiring harness between TCM and ABSCM/HU.
- Turn ignition on. Measure voltage between ground and ABSCM/HU connector terminal No. 3. See Figure
. If voltage is less than one volt, go to next step. If voltage is more than one volt, repair wiring harness between TCM and ABSCM/HU.
- Turn ignition off. Reconnect TCM connectors. Turn ignition on. Measure voltage between ground and TCM 20-pin connector terminal No. 5. See Fig 1
. If voltage is 10-15 volts, go to next step. If voltage is not 10-15 volts, transmission may not be functioning properly. Repair as necessary. If transmission is functioning properly, replace TCM.
Courtesy of SUBARU OF AMERICA, INC.
- Measure voltage between ground and ABSCM/HU connector terminals No. 3 and 31. See Figure
. If voltage is 10-15 volts, go to next step. If voltage is not 10-15 volts, repair wiring harness between TCM and ABSCM/HU.
- Check contacts at TCM and ABSCM/HU connectors. Clean contacts as needed. Go to next step.
- Turn ignition off. Reconnect all connectors. Erase memory. Recheck for trouble codes. If same trouble code returns, replace ABSCM/HU. If other trouble codes exist, go to proper test procedure. If no trouble codes exist, problem was a temporary poor contact. Recheck harness and connectors.