Diagnostic Test
- CHECK FOR DTC C1091-ABS BRAKE LAMP CONTROL CIRCUIT HIGH NOTE:
This DTC must be active for the results of this test to be valid.
- Turn the ignition on.
- With the scan tool, record and erase DTCs.
- Start the engine.
- Apply brake pedal firmly with at least 80 bar (1160 psi.).
- With the scan tool, read the DTCs.
Does the scan tool display: C1091-ABS BRAKE LAMP CONTROL CIRCUIT HIGH?
Yes
- Go To 2
No
- Perform the ABS-INTERMITTENT CONDITION TEST. Refer to ABS-INTERMITTENT CONDITION .
- CHECK CONNECTOR/TERMINAL FOR DAMAGE NOTE:
Check all terminals for broken, bent, pushed out or corroded terminals.
- Turn the ignition off.
- Inspect the Anti-Lock Brake Module harness connector and the Brake Lamp Activation Relay harness connector.
Is the ABM or any of the connectors/terminals damaged?
Yes
- Repair as necessary.
- Perform the ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .
No
- Go To 3
- CHECK (B122) BRAKE LAMP ACTIVATION RELAY CONTROL SHORTED TO VOLTAGE
- Turn the ignition off.
- Disconnect the ABM.
- Disconnect the Brake Lamp Activation Relay.
- Start the engine.
- Using a 12-volt test light connected to ground, probe the (B122) Brake Lamp Activation Relay Control at the Brake Lamp Activation Relay harness connector.
Does the test light illuminate brightly?
Yes
- Repair the short to voltage in the (B122) Brake Lamp Activation Relay Control Circuit.
- Perform the ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .
No
- Go To 4
- BRAKE LAMP ACTIVATION RELAY
- Turn the ignition off.
- Measure the resistance across the relay between the (B122) Brake Lamp Activation Relay Control Circuit and the ((A924) Fused B+ Circuit.
Is the resistance 75 - 95 Ohms?
Yes
- Replace the ABM in accordance with the Service Information.
- Perform the ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .
No
- Replace the Brake Lamp Activation Relay in accordance with the Service Information.
- Perform the ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .