C1090

C1090-ABS BRAKE LAMP CONTROL CIRCUIT LOW





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

NOTE: The Electronic Stability Control (ESC) may also be referred to as Electronic Stability Program (ESP) depending on the vehicle model year and configuration. Certain components may also reference ESP, ESC, or use the traction control symbol.

- When Monitored:
With the ignition on.

- 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 DTCs.
3. Start Engine.
4. Apply brake pedal firmly with at least 80 bar (1160 psi.).
5. With the scan tool, read DTCs.

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

Yes

- Go To 2

No

- Perform the ABS-INTERMITTENT CONDITION TEST. 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 ABS Module harness connector and the Brake Lamp Activation Relay harness connector.

Is the ABS 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 SHORTED TO GROUND




1. Turn the ignition off.
2. Disconnect the ABS Module harness connector.
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 ABS Module harness connector.

Does the test light illuminate brightly?

Yes

- Replace the Anti-Lock Brake System (ABS) 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.
- 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 ABS Module harness connector.

Is the resistance 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.