Diagnostic Test

1) GOOD TRIP INDICATED
NOTE: Verify battery voltage is greater than 9 volts.

Record Freeze Frame Data that was set by the related DTC before continuing.

With the DRBIII®, read DTCs.

Does the Good Trip Indicator display NO?

Yes
1. Go To 2).
No
1. Refer to the INTERMITTENT CONDITION diagnostic procedure.
2. Perform the POWERTRAIN VERIFICATION TEST. (Refer to STANDARD PROCEDURE - POWERTRAIN VERIFICATION TEST) .
2) (A924) FUSED B+

Fig 1: CHECKING FUSED B+ CIRCUIT FOR VOLTAGE
Courtesy of DAIMLERCHRYSLER CORP.

Turn ignition off.

Disconnect Brake Lamp Switch harness connector.

Turn the ignition on, engine not running.

Using a 12-volt test light connected to ground, check the (A924) Fused B+ circuit for voltage.

Does the test light illuminate brightly.

Yes
1. Go To 3).
No
1. Repair the open or short to ground in the (A924) Fused B+ circuit. Check the related fuse. If the fuse is open, check for a short to ground in the (A924) Fused B+ circuit.
2. Perform the POWERTRAIN VERIFICATION TEST. (Refer to STANDARD PROCEDURE - POWERTRAIN VERIFICATION TEST) .
3) (B15) BRAKE LAMP SWITCH SIGNAL CIRCUIT OPEN

Fig 2: CHECKING BRAKE LAMP SWITCH SIGNAL CIRCUIT
Courtesy of DAIMLERCHRYSLER CORP.

Turn the ignition off.

Disconnect the PCM harness connector.

Measure the resistance of the (B15) Brake Lamp Switch Signal circuit between the Brake Lamp Switch harness connector and the PCM harness connector.

Is the resistance below 5.0 ohms?

Yes
1. Go To 4).
No
1. Repair the open in the (B15) Brake Lamp Switch Signal circuit.
2. Perform the POWERTRAIN VERIFICATION TEST. (Refer to STANDARD PROCEDURE - POWERTRAIN VERIFICATION TEST) .
4) (B15) BRAKE LAMP SWITCH SIGNAL SHORTED TO GROUND

Fig 3: MEASURING RESISTANCE BETWEEN GROUND AND BRAKE LAMP SWITCH SIGNAL CIRCUIT
Courtesy of DAIMLERCHRYSLER CORP.

Measure the resistance between ground and the (B15) Brake Lamp Switch Signal circuit in the Brake Lamp Switch harness connector.

Is the resistance below 5.0 ohms?

Yes
1. Repair the short to ground in the (B15) Brake Switch Signal circuit.
2. Perform the POWERTRAIN VERIFICATION TEST. (Refer to STANDARD PROCEDURE - POWERTRAIN VERIFICATION TEST) .
No
1. Go To 5).
5) (Z902) GROUND CIRCUIT OPEN

Fig 4: CHECKING GROUND CIRCUIT
Courtesy of DAIMLERCHRYSLER CORP.

Using a 12-volt test light connected to 12-volts, probe the (Z902) Ground circuit in the Brake Lamp Switch harness connector.

Does the test light illuminate brightly?

Yes
1. Go To 6).
No
1. Repair the open in the (Z902) Ground circuit.
2. Perform the POWERTRAIN VERIFICATION TEST. (Refer to STANDARD PROCEDURE - POWERTRAIN VERIFICATION TEST) .
6) BRAKE LAMP SWITCH OPERATION

Fig 5: CHECKING BRAKE LAMP SWITCH OPERATION
Courtesy of DAIMLERCHRYSLER CORP.

Measure the resistance between the (Z902) Ground circuit terminal and the (B15) Brake Switch Signal terminal in the Brake Lamp Switch.

Apply and release the brake pedal while monitoring the ohmmeter.

Does the resistance change from below 5.0 ohms to open circuit?

Yes
1. Go To 7).
No
1. Replace the Brake Lamp Switch.
2. Perform the POWERTRAIN VERIFICATION TEST. (Refer to STANDARD PROCEDURE - POWERTRAIN VERIFICATION TEST) .
7) PCM
NOTE: Before Continuing: Disconnect the PCM harness connector and check the related wiring terminals for corrosion, damage or terminal push out. Repair as necessary.

Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.

If there are no possible causes remaining, view repair.

Repair
1. Replace and program the Powertrain Control Module in accordance with the Service Information. (Refer to STANDARD PROCEDURE - PCM/ECM/SKREEM PROGRAMMING) .
2. Perform the POWERTRAIN VERIFICATION TEST. (Refer to STANDARD PROCEDURE - POWERTRAIN VERIFICATION TEST) .