C1090

C1090-ABS BRAKE LAMP CONTROL CIRCUIT LOW





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

- When Monitored:
Continuous monitoring.

- Set Condition:
When monitoring the Brake Lamp Activation Relay Control 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 the DTCs.
3. Start engine.
4. Apply 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 diagnostic procedure. Component Tests and General Diagnostics.

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 Activation 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 (B401) BRAKE LAMP ACTIVATION RELAY CONTROL FOR A SHORT TO GROUND




1. Turn the ignition off.
2. Disconnect the Anti-Lock Brake Module.
3. Start the engine.
4. Using a 12-volt test light connected to ground, probe the (B401) Brake Lamp Activation Relay Control 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 (F941) FUSED RUN/START RELAY OUTPUT




1. Turn the ignition off.
2. Disconnect the Brake Lamp Activation Relay.
3. Start the engine.
4. Using a 12-volt test light connected to ground, probe the (F941) Fused Run/Start Relay Output Circuit at the Brake Lamp Activation 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 (F941) Fused Run/Start Relay Output Circuit or short to ground in (B401) Brake Lamp Activation Relay Control circuit.
- Perform the ABS VERIFICATION TEST. ABS Verification Test.

5. BRAKE LAMP ACTIVATION RELAY




1. Turn the ignition off.
2. Measure the resistance of the (B401) Brake Lamp Activation Relay Control circuit between the Brake Lamp Activation relay and the Anti-Lock Brake Module.

Is the resistance below 5 Ohms?

Yes

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

No

- Repair open in the (B401) Brake Lamp Activation Relay Control circuit.
- Perform the ABS VERIFICATION TEST. ABS Verification Test.