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 the DTCs.
3. Start the 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 step 2
  No
  - Perform the ABS-INTERMITTENT CONDITION TEST. See DTC-Based Diagnostics/MODULE, Antilock Brake (ABS) - 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 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. See DTC-Based Diagnostics/MODULE, Antilock Brake (ABS) - Standard Procedure .
  No
  - Go to step 3
CHECK (B221) BRAKE LAMP ACTIVATION RELAY CONTROL SHORTED TO GROUND

Fig 1: Checking Brake Lamp Activation Relay Control Circuit For Short To Ground
Courtesy of CHRYSLER LLC
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 (B221) 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 in accordance with the service information.
  - Perform the ABS VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Antilock Brake (ABS) - Standard Procedure .
  No
  - Go to step 4
CHECK (F943) FUSED IGNITION SWITCH OUTPUT

Fig 2: Checking Fused Ignition Switch Output Circuit
Courtesy of CHRYSLER 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 (F943) Fused Ignition Switch Output Circuit at the Brake Lamp Activation Relay harness connector.
  Does the test light illuminate brightly?
  
  Yes
  - Go to step 5
  No
  - Check for open Fuse, if ok repair open or short to ground in the (F943) Fused Ignition Switch Output Circuit or short to ground in (B221) Brake Lamp Activation Relay Control circuit.
  - Perform the ABS VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Antilock Brake (ABS) - Standard Procedure .
BRAKE LAMP ACTIVATION RELAY

Fig 3: Checking Brake Lamp Activation Relay Control Circuit Between Brake Lamp Activation Relay And Anti-Lock Brake Module
Courtesy of CHRYSLER LLC
1. Turn the ignition off.
2. 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 below 5 Ohms?
  
  Yes
  - Replace the Brake Lamp Activation Relay in accordance with the Service Information.
  - Perform the ABS VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Antilock Brake (ABS) - Standard Procedure .
  No
  - Repair open in the (B221) Brake Lamp Activation Relay Control circuit.
  - Perform the ABS VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Antilock Brake (ABS) - Standard Procedure .