Diagnostic Test

WARNING: This page is about a different car, the 2005 Jeep Grand Cherokee. However, it is still accessible from the selected car via links, so may be relevant.

1) ENGINE DTC'S PRESENT
With the scan tool, read Engine DTCs.

Are there any Engine brake DTC's present?

Yes
1. Refer to DTCS P0016 TO P0118, DIAGNOSTIC CODE INDEX, PRE-DIAGNOSTIC TROUBLESHOOTING, INTERMITTENT CONDITION and perform the appropriate diagnostic procedure.
2. Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1 .
No
1. Go To step 2).
2) ABS MODULE DTC'S PRESENT
With the scan tool, read ABS Module DTCs.

Are there any ABS DTC's present?

Yes
1. Refer to BRAKE CONTROLLER ELECTRICAL DIAGNOSTICS and perform the appropriate diagnostic procedure.
2. Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1 .
No
1. Go To step 3).
3) (B29) BRAKE SWITCH SIGNAL SHORT TO GROUND

Fig 1: Checking Brake Switch Signal For Short To Ground
Courtesy of DAIMLERCHRYSLER CORP.

Turn the ignition off to the lock position.

Disconnect the Shift Lever Assembly harness connector.

NOTE: Check connectors - Clean/repair as necessary.

Measure the resistance between ground and the (B29) Brake Switch Signal circuit.

Is the resistance below 5.0 ohms?

Yes
1. Repair the (B29) Brake Switch Signal for a short to ground.
No
1. Go To step 4).
4) SHIFT LEVER ASSEMBLY
Using the schematics as a guide, inspect the wiring and connectors. Repair as necessary. Pay particular attention to all power and ground circuits.

If there are no possible causes remaining, view repair.

Repair
1. Replace the Shift Lever Assembly per the Service Information.
2. Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1 .