C1090

C1090-ABS BRAKE LAMP CONTROL CIRCUIT LOW

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

- 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. ABS Intermittent Condition Test.

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 ABM 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 (B122) BRAKE LAMP ACTIVATION RELAY CONTROL SHORTED TO GROUND




1. Turn the ignition off.
2. Disconnect the ABM.
3. Start the engine.
4. Using a 12-volt test light connected to ground, probe the (B122) Brake Lamp Activation Relay Control Circuit at the ABM harness connector.

Does the test light illuminate?

Yes

- Replace the ABM in accordance with the Service Information.
- Perform the ABS VERIFICATION TEST. ABS Verification Test.

No

- Go To 4

4. CHECK (A924) FUSED B+




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 (A924) Fused B+ 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 okay repair open or short to ground in the (A924) Fused B+ Circuit or short to ground in (B122) 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 (B122) Brake Lamp Activation Relay Control Circuit between the Brake Lamp Activation relay and the ABM.

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 (B122) Brake Lamp Activation Relay Control circuit.
- Perform the ABS VERIFICATION TEST. ABS Verification Test.