P2504

P2504-CHARGING SYSTEM OUTPUT HIGH





For a complete wiring diagram Refer to Diagrams/Electrical.

Theory of Operation


There are two communication lines between the ECM and alternator. Based on sensed battery voltage, the ECM commands the alternator to charge the batteries to a desired voltage. The max voltage the ECM will command the alternator to charge is 14.75-volt. The ECM then receives feedback from the alternator on the voltage level it is charging the batteries. The ECM will not light a MIL lamp for this fault.

- When Monitored:
While the engine is running.

- Set Condition:
Battery voltage is less than 11.5 volts for more than 8 seconds. Battery voltage must exceed 12 volts for more than 5 seconds for fault to become inactive.







Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Initial Inspection and Diagnostic Overview


Diagnostic Test


1. ACTIVE DTC
With the scan tool, read DTCs.
Is DTC P065A active

Yes


- Go To 2


No


- Refer to the INTERMITTENT CONDITION - DIESEL Diagnostic Procedure. Intermittent Condition .



2. DIRTY OR LOOSE CONNECTIONS
Visually inspect the positive and negative connections at the battery.
Visually inspect the battery negative connections at the engine block.
Are the connections free of corrosion and are they tight?

Yes


- Go To 3


No


- Clean and/or tighten the connections.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test



3. ADD-ON OR ACCESSORY WIRES AT BATTERY TERMINAL
Check for add-on or accessory wiring at positive (+) terminal of the battery.
Are there any damaged wires at the battery?

Yes


- Remove defective or miss wired add-on or accessory wiring from battery.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test


No


- Go To 4



4. HIGH RESISTANCE IN THE B+ CIRCUIT
Measure the voltage between the B+ post of the generator and the B+ post of the battery while the engine is running.
Is the voltage above.4 volts?

Yes


- Repair the high resistance in the B+ circuit from battery to the generator.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test


No


- Go To 5



5. HIGH RESISTANCE IN THE B+ CROSS OVER CABLE
Measure the voltage between the B+ post of the generator and the B+ post of the right side battery to the left side battery while the engine is running.
Is the voltage above.4 volts?

Yes


- Repair the high resistance in the B+ cross over cable from right side battery to left side battery.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test


No


- Go To 6



6. HIGH RESISTANCE IN THE GROUND CIRCUIT
Measure the voltage between the generator case and the B- post of the battery.
Is the voltage above.1 volts?

Yes


- Repair the high resistance in the ground circuit.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test


No


- Go To 7



7. GENERATOR
Disconnect the Generator field harness connector.

NOTE: Check connectors - Clean/repair as necessary.

Measure the resistance between the generator field terminals at the generator.
Is the resistance between.5 and 15 Ohms?

Yes


- Go To 8


No


- Replace the generator.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test



8. ECM
Measure and record the voltage between battery positive circuit of the ECM harness connector and the battery negative circuits of the ECM harness connector.
Reconnect the ECM connectors.
Use the scan tool to measure and record battery voltage.
Compare the voltage reading from the voltmeter with that of the scan tool.
Are the readings within 3 volts of each other?

Yes


- Refer to the INTERMITTENT CONDITION - DIESEL Diagnostic Procedure. Intermittent Condition


No


- Replace and program the ECM.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test