Diagnostic Test

WARNING: This page is about a different car, the 2012 RAM Cab & Chassis. 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. Ignition on, engine not running.
2. With the scan tool, record and erase DTC's.
3. Start the engine.
4. Apply brake pedal firmly with at least 80 bar (1160 psi.).
5. With the scan tool, read DTC's.
  Does the scan tool display: C1091-ABS BRAKE LAMP CONTROL CIRCUIT HIGH?
  
  Yes
  - Go To 2.
  No
  - Perform the ABS INTERMITTENT CONDITION diagnostic procedure. Refer to ABS INTERMITTENT CONDITION .
CHECK CONNECTOR/TERMINAL FOR DAMAGE
NOTE:
Check all terminals for broken, bent, pushed out, or corroded terminals.
1. Turn ignition off to the lock position.
2. Inspect the Antilock Brake System (ABS) Module harness connector and the Brake Lamp Activation Relay harness connector.
  Is the Antilock Brake System (ABS) Module or any of the connectors/terminals damaged?
  
  Yes
  - Repair as necessary.
  - Perform the ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .
  No
  - Go To 3.
CHECK (B401) BRAKE LAMP ACTIVATION RELAY CONTROL SHORTED TO VOLTAGE

Fig 1: Checking Brake Lamp Activation Relay Control For A Short To Voltage
Courtesy of CHRYSLER GROUP, LLC
1. Turn ignition off to the lock position.
2. Disconnect the ABS Module.
3. Disconnect the Brake Lamp Activation Relay.
4. Ignition on, engine not running.
5. Using a 12-volt test light connected to ground, probe the (B401) Brake Lamp Activation Relay Control Circuit at the Brake Lamp Activation Relay harness connector.
  Does the test light illuminate brightly?
  
  Yes
  - Repair the short to voltage in the (B401) Brake Lamp Inhibit Relay Control circuit.
  - Perform the ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .
  No
  - Go To 4.
BRAKE LAMP ACTIVATION RELAY

Fig 2: Checking Brake Lamp Activation Relay Control Circuit
Courtesy of CHRYSLER GROUP, LLC
1. Turn ignition off to the lock position.
2. Measure the resistance across the relay between the (B401) Brake Lamp Activation Relay Control Circuit and the (A108) Fused B(+) at the Brake Lamp Activation Relay harness connector.
  Is the resistance 75 Ohms ±5 Ohms?
  
  Yes
  - Replace the Antilock Brake System (ABS) Module in accordance with the service information.
  - Perform the ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .
  No
  - Replace the Brake Lamp Activation Relay in accordance with the Service Information.
  - Perform the ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .