Diagnostic Test

1) ACTIVE DTC
Ignition on, engine not running.

With a scan tool, read DTCs.

Is the DTC active at this time?

Yes
1. Go To step 2).
No
1. Refer to INTERMITTENT CONDITION .
2. Perform POWERTRAIN VERIFICATION TEST .
2) GENERATOR OPERATION

Fig 1: Checking Generator Operation
Courtesy of DAIMLERCHRYSLER CORP.

Turn the ignition off.

Disconnect the Generator Field harness connector.

Using a 12-volt test light, jump it across the Generator Field harness connector.

Ignition on, engine not running.

With the scan tool, actuate the Generator Field Control circuit.

Does the test light illuminate brightly and flash on and off?

Yes
1. Replace the Generator.
2. Perform POWERTRAIN VERIFICATION TEST .
No
1. Go To step 3).
3) (K125) GEN FIELD CIRCUIT SHORTED BATTERY VOLTAGE

Fig 2: Checking Generator Field Circuit For Short To Battery Voltage
Courtesy of DAIMLERCHRYSLER CORP.

Turn the ignition off.

Disconnect the C2 PCM harness connector.

Ignition on, engine not running.

Measure the voltage on the (K125) Gen Field Control circuit in the Generator Field harness connector.

Is the voltage above 0 volts?

Yes
1. Repair the short to battery voltage in the (K125) Gen Field Control circuit.
2. Perform POWERTRAIN VERIFICATION TEST .
No
1. Go To step 4).
4) (K125) GEN FIELD CIRCUIT OPEN

Fig 3: Checking Generator Field Control Circuit
Courtesy of DAIMLERCHRYSLER CORP.

Turn the ignition off.

CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis.

Measure the resistance of the (K125) Gen Field Control circuit from the Generator Field harness connector to appropriate terminal of the special tool #8815.

Is the resistance below 5.0 ohms?

Yes
1. Go To step 5).
No
1. Repair the open in the (K125) Gen Field Control circuit.
2. Perform POWERTRAIN VERIFICATION TEST .
5) (K125) GEN FIELD CIRCUIT SHORTED TO GROUND

Fig 4: Checking Generator Field Control Circuit For Short To Ground
Courtesy of DAIMLERCHRYSLER CORP.

Measure the resistance between ground and the (K125) Gen Field Control circuit in the Generator Field harness connector.

Is the resistance below 100 ohms?

Yes
1. Repair the short to ground in the (K125) Gen Field Control circuit.
2. Perform POWERTRAIN VERIFICATION TEST .
No
1. Go To step 6).
6) (Z385) GROUND CIRCUIT OPEN

Fig 5: Checking Ground Circuit Open
Courtesy of DAIMLERCHRYSLER CORP.

Using a 12-volt test light connected to battery voltage, probe the (Z385) Ground circuit in the Gen Field harness connector.

Does the test light illuminate brightly?

Yes
1. Go To step 7).
No
1. Repair the open in the (Z385) Ground circuit.
2. Perform POWERTRAIN VERIFICATION TEST .
7) PCM
NOTE: Before continuing, check the PCM harness connector 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.

Were there any problems found?

Yes
1. Repair as necessary.
2. Perform POWERTRAIN VERIFICATION TEST .
No
1. Replace and program the Powertrain Control Module per Service Information.
2. Perform POWERTRAIN VERIFICATION TEST .