Diagnostic Test

WARNING: This page is about a different car, the 2010 Dodge Charger and 2010 Chrysler 300. However, it is still accessible from the selected car via links, so may be relevant.

CHECK FOR DTC C1091-ABS BRAKE LAMP CONTROL CIRCUIT HIGH
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: C1091-ABS BRAKE LAMP CONTROL CIRCUIT HIGH?
  
  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 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) STOP LAMP RELAY OVERRIDE SIGNAL SHORTED TO VOLTAGE

Fig 1: Checking Stop Lamp Relay Override Signal For Short To Voltage
Courtesy of CHRYSLER LLC
1. Turn the ignition off.
2. Disconnect the Anti-Lock Brake Module.
3. Disconnect the Brake Lamp Relay.
4. Turn the ignition on.
5. Using a 12-volt test light connected to ground, probe the (B221) Stop Lamp Relay Override Signal circuit at the Brake Lamp Relay harness connector.
  Does the test light illuminate brightly?
  
  Yes
  - Repair the short to voltage in the (B221) Stop Lamp Relay Override Signal circuit.
  - Perform the ABS VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Antilock Brake (ABS) - Standard Procedure .
  No
  - Go to step 4
BRAKE LAMP RELAY

Fig 2: Checking Stop Lamp Relay Override Signal Circuit
Courtesy of CHRYSLER LLC
1. Turn the ignition off.
2. Measure the resistance across the relay between the (B221) Stop Lamp Relay Override Signal circuit and the (A103) Fused B+ circuit.
  Is the resistance 75 Ohms ±5 Ohms?
  
  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
  - Replace the Brake Lamp Relay in accordance with the Service Information.
  - Perform the ABS VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Antilock Brake (ABS) - Standard Procedure .