Diagnostic Test

1) ACTIVE DTC
NOTE: Inspect the vehicle for aftermarket accessories that may exceed the Generator System output.

Ignition on, engine not running.

NOTE: The battery must be fully charged.

NOTE: The Generator belt tension and condition must be checked before continuing.

With a scan tool, read DTCs.

With a scan tool, erase DTCs.

Start the engine.

Allow the idle to stabilize.

With the scan tool, read DTCs.

Is the DTC active at this time?

Yes
1. Go To 2).
No
1. Refer to the INTERMITTENT CONDITION diagnostic procedure.
2. Perform the POWERTRAIN VERIFICATION TEST. (Refer to POWERTRAIN VERIFICATION TEST)
2) FUSED B+ CIRCUIT HIGH RESISTANCE
NOTE: Inspect the Generator harness connector and the Generator Eyelet for corrosion or damage before continuing.

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.

Ignition on, engine not running.

NOTE: Make sure all wires are clear of the engine's moving parts.

Measure the voltage between the Generator B+ Output Terminal and the Battery(+) Post.

Start the engine.

Is the voltage above 0.4 of a volt?

Yes
1. Repair the excessive resistance in the battery positive circuit between the Generator and Battery.
2. Perform the POWERTRAIN VERIFICATION TEST. (Refer to POWERTRAIN VERIFICATION TEST)
No
1. Go To 3).
3) EXCESSIVE RESISTANCE IN THE CASE GROUND
WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.

Start the engine.

Warm the engine to operating temperature.

NOTE: Make sure all wires are clear of the engine's moving parts.

Measure the voltage between the Generator Case and Battery ground post.

Is the voltage above 0.1 of a volt?

Yes
1. Repair the excessive resistance in the Generator Case Ground.
2. Perform the POWERTRAIN VERIFICATION TEST. (Refer to POWERTRAIN VERIFICATION TEST)
No
1. Go To 4).
4) (A803/A804) GEN SENSE CIRCUIT SHORTED TO BATTERY VOLTAGE

Fig 1: MEASURING FOR VOLTAGE ON THE GEN SENSE CIRCUITS
Courtesy of DAIMLERCHRYSLER CORP.

Turn the ignition off.

Disconnect the Generator harness connector.

Disconnect the PCM harness connectors.

Turn the ignition on.

Measure the voltage on the (A803/A804) Gen Sense circuit in the Generator Field harness connector.

Does the voltameter indicate voltage present?

Yes
1. Repair the short to battery voltage in the (A803/A804) Gen Sense circuit.
2. Perform the POWERTRAIN VERIFICATION TEST. (Refer to POWERTRAIN VERIFICATION TEST)
No
1. Go To 5).
5) INTERNAL HIGH RESISTANCE GENERATOR
WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.

Turn the ignition off.

Reconnect the Generator harness connector.

Reconnect the PCM Harness connector.

NOTE: Make sure all wires are clear of the engine's moving parts.

Measure the voltage between the Generator Eyelet terminal and the Gen Sense circuit in the Generator harness connector.

Start the engine.

Is the voltage above 0.1 of a volt?

Yes
1. Replace the Generator in accordance with the Service Information.
2. Perform the POWERTRAIN VERIFICATION TEST. (Refer to POWERTRAIN VERIFICATION TEST)
No
1. Replace the Powertrain Control Module in accordance with the Service Information.
2. Perform the POWERTRAIN VERIFICATION TEST. (Refer to POWERTRAIN VERIFICATION TEST)