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 A DTC C121E-BRAKE PRESSURE SENSOR COMPARATIVE PERFORMANCE
2. Turn the ignition on.
3. With the scan tool, read and record DTC's.
4. With the scan tool, read and record Freeze Frame information.
5. With the scan tool, erase DTC's.
6. Start the engine.
7. Depress and release the brake pedal.
8. With the scan tool, read and record DTC's.
  Does the scan tool display: C121E-BRAKE PRESSURE SENSOR COMPARATIVE PERFORMANCE?
  
  Yes
  - Go To 2.
  No
  - Perform the ABS INTERMITTENT CONDITION diagnostic procedure. Refer to ABS INTERMITTENT CONDITION .
CHECK BRAKE SWITCH
1. With the scan tool look at the Brake Switch Signal.
2. Apply the brakes on and off while checking for a Brake Switch Signal change.
  Did the Brake Switch Signal change?
  
  Yes
  - Go To 3.
  No
  - Repair as needed.
CHECK BRAKE PRESSURE SENSOR
1. With the scan tool look at Pressure Sensor Signal and the Brake Switch Signal.
2. With the brakes not applied the Pressure Sensor should read ± 15 bar (218 psi).
3. Apply the brakes hard, the Pressure Sensor should read above 15 bar (218 psi).
  Did Brake Pressure Sensor increase above 15 bar (218 psi)?
  
  Yes
  - Replace the Integrated Control Unit in accordance with the Service Information.
  - Perform the ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .
  No
  - Go To 4.
CHECK FOR AIR IN BRAKE SYSTEM
NOTE:
Before continuing the brake system must be bled to verify there is no air in the brake system.
1. Turn ignition off.
2. Bleed brake system.
  Was there any air in the brake system?
  
  Yes
  - Repair as needed.
  - Perform the ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .
  No
  - Replace the Integrated Control Unit in accordance with the Service Information.
  - Perform the ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .