P2502
P2502-CHARGING SYSTEM ERRORP2502 - Charging System Error:
WHEN MONITORED
While the engine is running.
SET CONDITION
The ECM cycles the voltage regulator in the generator while monitoring for a change in output voltage. If the voltage does not drop when the regulator is off, the fault is set.
POSSIBLE CAUSES
- Dirty or loose connections
- High resistance in the B+ circuit
- High resistance in the B+ cross over cable
- High resistance in the ground circuit
- Generator
- ECM
- Intermittent condition
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.
Diagnostic Test
1. DIRTY OR LOOSE CONNECTIONS
Visually inspect the positive and negative connections at the battery.
Visually inspect the battery negative connections at the engine block.
Q: Are the connections free of corrosion and are they tight?
YES: Go To 2
NO: Clean and/or tighten the connections. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1
2. 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.
Q: Is the voltage above .4 volts?
YES: Repair the high resistance in the B+ circuit from battery to the generator. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1
NO: Go To 3
3. 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.
Q: 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 the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1
NO: Go To 4
4. HIGH RESISTANCE IN THE GROUND CIRCUIT
Measure the voltage between the generator case and the B- post of the battery.
Q: Is the voltage above .1 volts?
YES: Repair the high resistance in the ground circuit. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1
NO: Go To 5
5. GENERATOR
Disconnect the Generator field harness connector.
NOTE: Check connectors - Clean/repair as necessary.
Measure the resistance between the generator field terminals.
Q: Is the resistance between .5 and 15 Ohms?
YES: Go To 6
NO: Replace the generator. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1
6. All
Turn the ignition off.
Reconnect the Generator field harness connector.
Disconnect the ECM harness connectors.
NOTE: Check connectors - Clean/repair as necessary.
Ignition on, engine not running.
Measure and record the voltage between battery positive circuits of the ECM harness connector and the battery negative circuits of the ECM harness connector.
Turn the ignition off.
Reconnect the ECM harness connectors.
Start the engine.
Use the scan tool to measure and record battery voltage.
Compare the voltage reading from the voltmeter with that of the scan tool.
Q: Are the readings within 3 volts of each other?
YES: Test Complete.
NO: Replace and program the ECM in accordance with the Service Information. Perform the POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). Powertrain Verification Test - Ver 1