DTC 77-4

77-4: Communication Error with the Automatic-Transmission Control Unit

NOTE: Before you troubleshoot, review the general troubleshooting information.

1. Turn the ignition switch ON (II).
2. Clear the DTC with the HDS.
3. Start the engine.
4. Check for DTCs with the HDS.

Is DTC 77-4 indicated?

YES - Go to step 5.

NO - Intermittent failure, the system is OK at this time.

5. Check for DTCs in the A/T system with the HDS.

Are any A/T system DTCs indicated?

YES - Go to the indicated DTC's troubleshooting.

NO - Update the SH-AWD control unit if it does not have the latest software or substitute a known-good SH-AWD control unit and recheck. If the symptom/indication goes away with the updated SH-AWD control unit, troubleshooting is complete. If the symptom/indication goes away with a known-good SH-AWD control unit, replace the original SH-AWD control unit.