C1090

C1090-ABS BRAKE LAMP CONTROL CIRCUIT LOW





For a complete wiring diagram, refer to the Wiring Information. Electrical Diagrams

- When Monitored:
With the ignition on.

- Set Condition:
When monitoring the Stop Lamp Relay Override Signal circuit the module detects a short to ground.





1. CHECK FOR DTC C1090-ABS BRAKE LAMP CONTROL CIRCUIT LOW

NOTE: This DTC must be active for the results of this test to be valid.

1. Turn the ignition on.
2. With the scan tool, record and erase DTCs.
3. Start the engine.
4. Apply pressure to the brake pedal firmly with at least 80 bar (1160 psi.).
5. With the scan tool, read the DTCs.

Does the scan tool display: C1090-ABS BRAKE LAMP CONTROL CIRCUIT LOW?

Yes

- Go To 2

No

- Perform the ABS-INTERMITTENT CONDITION TEST. Testing and Inspection.

2. CHECK CONNECTOR/TERMINAL FOR DAMAGE

NOTE: Check all terminals for broken, bent, pushed out or corroded terminals.

1. Turn the ignition off.
2. Inspect the Anti-Lock Brake Module harness connector and the Brake Lamp Relay harness connector.

Is the Anti-Lock Brake Module or any of the connectors/terminals damaged?

Yes

- Repair as necessary.
- Perform the ABS VERIFICATION TEST. ABS Verification Test.

No

- Go To 3

3. CHECK (B221) STOP LAMP RELAY OVERRIDE SIGNAL SHORTED TO GROUND




1. Turn the ignition off.
2. Disconnect the Anti-Lock Brake Module
3. Turn the key on.
4. Using a 12-volt test light connected to ground, probe the (B221) Stop Lamp Relay Override Signal circuit at the Anti-Lock Brake Module harness connector.

Does the test light illuminate?

Yes

- Replace the Anti-Lock Brake Module.
- Perform the ABS VERIFICATION TEST. ABS Verification Test.

No

- Go To 4

4. CHECK (A103) FUSED B+




1. Turn the ignition off.
2. Disconnect the Brake Lamp Relay.
3. Turn the key on.
4. Using a 12-volt test light connected to ground, probe the (A103) Fused B+ circuit at the Brake Lamp Relay harness connector.

Does the test light illuminate brightly?

Yes

- Go To 5

No

- Check for open fuse, if ok repair open or short to ground in the (A103) Fused B+ circuit.
- Perform the ABS VERIFICATION TEST. ABS Verification Test.

5. BRAKE LAMP RELAY




1. Turn the ignition off.
2. Measure the resistance of the (B221) Stop Lamp Relay Override Signal Circuit between the Brake Lamp Relay and the Anti-Lock Brake Module.

Is the resistance below 5 Ohms?

Yes

- Replace the Brake Lamp Relay.
- Perform the ABS VERIFICATION TEST. ABS Verification Test.

No

- Repair open in the (B221) Brake Lamp Inhibit Relay Control circuit.
- Perform the ABS VERIFICATION TEST. ABS Verification Test.