DTC U1040: Loss Of Class 2 Communication With Abs
WARNING: This page is about a different car, the 1999 Pontiac Grand Am and 1999 Oldsmobile Alero. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
If circuit is shorted to ground, fuse will blow. Check fuse before performing diagnostics.
- Test battery positive voltage circuits to Electronic Brake Control Module (EBCM) for open or short to ground conditions. See appropriate POWER DISTRIBUTION wiring diagram under WIRING DIAGRAMS. If faulty circuit is found and repaired, go to step 5 . If circuits are okay, go to next step.
- Test ground circuits to EBCM for open conditions. See appropriate GROUND DISTRIBUTION wiring diagram under WIRING DIAGRAMS. If faulty circuit is found and repaired, go to step 5 . If circuits are okay, go to next step.
- Check for poor connection of power or ground circuits at EBCM connectors. If poor connections are found and repaired, go to step 5 . If connections are okay, go to next step.
- Replace EBCM. After repairs, go to next step.
- Using scan tool, check EBCM DTCs. If scan tool shows any DTCs for EBCM that begin with "U", go to appropriate DTC diagnosis and repair procedure in appropriate ANTI-LOCK BRAKES article in BRAKES. If scan tool does not show any DTCs for EBCM that begin with "U", go to next step.
- Using scan tool, clear DTCs. Continue diagnosing and clearing DTCs until all DTCs have been cleared. After repairs, go to DATA LINK CONNECTIONS DIAGNOSTIC SYSTEM CHECK under SYSTEM TESTS.