No Response From Controller Anti-Lock Brake
NOTE:
After making any repairs, perform ABS VERIFICATION TEST under VERIFICATION TESTS.
- Turn ignition on. Using scan tool, attempt to communicate with Occupant Restraint Controller (ORC) and Body Control Module (BCM). If scan tool identifies or communicates with any module, go to next step. If scan tool does not identify or communicate with any module, go to PCI BUS COMMUNICATION FAILURE .
- Turn ignition off. Disconnect Controller Anti-Lock Brake (CAB) connector. See Fig 1. Using a 12-volt test light connected to 12 volts, probe both ground circuits. If the test light illuminated for each circuit, go to the next step. If the test light did not illuminate for each circuit, repair the ground circuits for an open.
- Turn the ignition off. Disconnect the CAB harness connector. See Fig 1. Turn the ignition on. Using a 12-volt test light connected to ground, probe the fused ignition switch output circuits. If the test light illuminated, go to the next step. If the test light did not illuminate, repair the fused ignition switch output circuit for an open.
- Obtain Scope Input Cable (CH7058), Cable To Probe Adapter (CH7062) and Red and Black test probes. Connect scope input cable to channel 1 connector on scan tool. Connect Red and Black test probes and probe adapter to scope input cable. Select PEP MODULE TOOLS on scan tool. Select LAB SCOPE then LIVE DATA. Select 12V SQUARE WAVE. Press F2 for scope then enter to select channel. Press F2 again and use down arrow to set voltage range to 20 volts. Set probe to x10. Press F2 again to complete. Connect Black probe to ground and Red probe to CAB connector terminal No. 5. Turn ignition on. Monitor scope on scan tool. If voltage pulses between zero and 7.5 volts, go to next step. If voltage does not pulse between zero and 7.5 volts, repair open in White/Violet wire (PCI bus circuit) between CAB and diagnostic junction port terminal No. 9. See Figure.
- If there are no possible causes remaining, replace the controller anti-lock brake. See appropriate ANTI-LOCK article in BRAKES.