C1090

C1090-ABS BRAKE LAMP CONTROL CIRCUIT LOW

For a complete wiring diagram consult Diagrams/Electrical.






- When Monitored:
With the ignition on.

- Set Condition:
When monitoring the Brake Lamp Activation Relay Control circuit the module detects a short to ground.








Diagnostic Test


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.

Turn the ignition on.
With the scan tool, record and erase DTCs.
Start Engine.
Apply brake pedal firmly with at least 80 bar (1160 psi.).
With the scan tool, read DTCs.
Does the scan tool display: C1090-ABS BRAKE LAMP CONTROL CIRCUIT LOW?

Yes


- Go To 2


No



- Refer to 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.

Turn the ignition off.
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 ABS VERIFICATION TEST. ABS Verification Test


No


- Go To 3




3. CHECK (B221) BRAKE LAMP ACTIVATION RELAY CONTROL SHORTED TO GROUND




Turn the ignition off.
Disconnect the Anti-Lock Brake Module
Key on.
Using a 12-volt test light connected to ground, probe the (B221) Brake Lamp Activation Relay Control Circuit at the Anti-Lock Brake Module harness connector.
Does the test light illuminate brightly?

Yes


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


No


- Go To 4




4. CHECK (A103) FUSED IGNITION SWITCH OUTPUT




Turn the ignition off.
Disconnect the Brake Lamp Activation Relay.
Key on.
Using a 12-volt test light connected to ground, probe the (A103) Fused Ignition Switch 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 (A103) Fused Ignition Switch Output Circuit.
- Perform ABS VERIFICATION TEST. ABS Verification Test




5. BRAKE LAMP ACTIVATION RELAY




Turn the ignition off.
Measure the resistance of the (B221) Brake Lamp Activation Relay Control Circuit between the Brake Lamp Activation relay and the Anti-Lock Brake Module.
Is the resistance 5 ohms ?

Yes


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


No


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