Diagnostic Test

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. Refer to STANDARD PROCEDURE .
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. Refer to STANDARD PROCEDURE .
  No
  - Go To 3
CHECK (B401) BRAKE LAMP ACTIVATION RELAY CONTROL SHORTED TO GROUND

Fig 1: Probing Brake Lamp Activation Relay Control Circuit Using 12-Volt Test Light Connected To Ground
Courtesy of CHRYSLER GROUP, LLC
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 in accordance with the service information.
  - Perform the ABS VERIFICATION TEST. Refer to STANDARD PROCEDURE .
  No
  - Go To 4
CHECK (F941) FUSED RUN/START RELAY OUTPUT

Fig 2: Checking Fused Run/Start Relay Output Circuit Using 12-Volt Test Light Connected To Ground
Courtesy of CHRYSLER GROUP, LLC
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. Refer to STANDARD PROCEDURE .
BRAKE LAMP ACTIVATION RELAY

Fig 3: Measuring Resistance Of Brake Lamp Activation Relay Control Circuit
Courtesy of CHRYSLER GROUP, LLC
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 in accordance with the Service Information.
  - Perform the ABS VERIFICATION TEST. Refer to STANDARD PROCEDURE .
  No
  - Repair open in the (B401) Brake Lamp Activation Relay Control circuit.
  - Perform the ABS VERIFICATION TEST. Refer to STANDARD PROCEDURE .