Diagnostic Test

WARNING: This page is about a different car, the 2012 Jeep Liberty. However, it is still accessible from the selected car via links, so may be relevant.

ENGINE DTCs PRESENT
1. With the scan tool, read Engine DTCs.
  Are there any Engine brake DTCs present?
  
  Yes
  - Refer to DIAGNOSTIC CODE INDEX and perform the appropriate diagnostic procedure.
  - Refer to STANDARD PROCEDURE and perform the NAG1 TRANSMISSION VERIFICATION TEST.
  No
  - Go To 2.
ABS MODULE DTCs PRESENT
1. With the scan tool, read ABS Module DTCs.
  Are there any ABS DTCs present?
  
  Yes
  - Refer to DIAGNOSTIC CODE INDEX and perform the appropriate diagnostic procedure.
  - Refer to STANDARD PROCEDURE and perform the NAG1 TRANSMISSION VERIFICATION TEST.
  No
  - Go To 3.
(L51) BRAKE SWITCH SIGNAL OPEN

Fig 1: Checking Brake Switch Signal For Open
Courtesy of CHRYSLER GROUP, LLC
1. Turn the ignition off to the lock position.
2. Disconnect the Shift Lever Assembly harness connector.
3. Disconnect the Stop Lamp Switch harness connector.
  NOTE:
  Check connectors - Clean/repair as necessary.
4. Measure the resistance of the (L51) Brake Switch Signal circuit between the Shift Lever Assembly harness connector and the Stop Lamp Switch.
  Is the resistance above 5.0 ohms?
  
  Yes
  - Repair the (L51) Brake Switch Signal for an open.
  - Refer to STANDARD PROCEDURE and perform the NAG1 TRANSMISSION VERIFICATION TEST.
  No
  - Go To 4.
(L51) BRAKE SWITCH SIGNAL SHORT TO VOLTAGE

Fig 2: Checking Brake Switch Signal For Short To VOLTAGE
Courtesy of CHRYSLER GROUP, LLC
1. Turn the ignition off to the lock position.
2. Disconnect the Shift Lever Assembly harness connector.
  NOTE:
  Check connectors - Clean/repair as necessary.
3. Turn the ignition on.
4. Measure the VOLTAGE of the (L51) Brake Switch Signal circuit.
  Is the VOLTAGE above 0.5 volts?
  
  Yes
  - Repair the (L51) Brake Switch Signal for a short to VOLTAGE.
  - Refer to STANDARD PROCEDURE and perform the NAG1 TRANSMISSION VERIFICATION TEST.
  No
  - Replace the Shift Lever Assembly in accordance with the Service Information.
  - Refer to STANDARD PROCEDURE and perform the NAG1 TRANSMISSION VERIFICATION TEST.