DTC U1040: Loss Of EBCM/EBTCM Communication: Testing
- If instrument cluster diagnostic system check was performed, go to next step. If instrument cluster diagnostic system check was not performed, go to INSTRUMENT CLUSTER DIAGNOSTIC SYSTEM CHECK under SYSTEM TESTS.
- Connect scan tool. Turn ignition switch to RUN position. Using scan tool, establish communication with EBCM/EBTCM. If communication can be established, go to step 9 . If communication cannot be established, go to next step.
- Using scan tool, establish communication with other modules on class 2 serial data line. If communication can be established, go to next step. If communication cannot be established, go to SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DATA LINE .
- Check for poor connection at EBCM/EBTCM Light Gray 24-pin connector C1, terminal A1 (Light Blue wire). Repair as necessary and go to step 9 . If circuit is okay, go to next step.
- Disconnect EBCM/EBTCM connector C1. Disconnect splice pack SP205 connector. See COMPONENT LOCATIONS . Using DVOM, check resistance between splice pack SP205 connector terminal "E" (Light Blue wire) and EBCM/EBTCM harness connector C1, terminal A1 (Light Blue wire). See Figure . If resistance is 0-3 ohms, go to next step. If resistance is not 0-3 ohms, go to step 7 .
- Check resistance between EBCM/EBTCM harness connector C1, terminal A1 (Light Blue wire) and ground. See Figure . If resistance is 0-3 ohms, go to next step. If resistance is not 0-3 ohms, go to step 8 .
- Repair open or short to ground in appropriate circuit. See WIRING DIAGRAMS . Go to step 9 .
- Turn ignition switch to OFF position. Replace EBCM/EBTCM. See appropriate ANTI-LOCK/TCS article in BRAKES. Go to next step.
- Turn ignition switch to OFF position. Reconnect all connectors and components. Using scan tool, clear DTCs. Recheck system operation.