P2503
P2503-CHARGING SYSTEM OUTPUT LOW
For a complete wiring diagram Refer to the Wiring Information.
- When Monitored:
With the engine speed greater than 1157 RPM.
- Set Condition:
The PCM detects that battery voltage is 1 volt below charging goal voltage for 13.47 seconds. The PCM compares sensed battery voltage with the field driver on and off. If the voltages are the same, this code will set. One Trip Fault. Three good trips to turn off the MIL.
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.
1. DTC IS ACTIVE
NOTE: Inspect the vehicle for aftermarket accessories that may exceed the generator system output.
NOTE: Inspect the condition and tension of the generator belt before continuing.
NOTE: Inspect the battery before continuing.
1. Ignition on, engine not running.
2. With a scan tool, select View DTCs. Record DTC and Freeze Frame information
3. With a scan tool, clear DTCs.
4. Start the engine and allow it to reach operating temperature.
5. With the scan tool, select View DTCs.
Is the status Active for this DTC?
Yes
- Go to 2
No
- Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure.Checking for an Intermittent DTC
2. EXCESSIVE RESISTANCE IN THE B(+) CIRCUIT
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 may result in possible serious or fatal injury.
NOTE: Make sure all test equipment and cables are clear of any belts, pulleys, or other moving parts.
1. Monitor the voltage between the generator B(+) output terminal and the battery positive (+) post.
2. Start the engine.
Is the voltage above 0.4 volts?
Yes
- Repair the battery positive (+) circuit between the generator and battery for high resistance.
- Perform the PCM Verification TestPCM Verification Test
No
- Go to 3
3. EXCESSIVE RESISTANCE BETWEEN THE GENERATOR CASE AND 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 may result in possible serious or fatal injury.
NOTE: Make sure all test equipment and cables are clear of any belts, pulleys, or other moving parts.
1. Monitor the voltage between the generator case and battery ground (-) post.
2. Start the engine and allow it to reach operating temperature.
Is the voltage above 0.1 volts?
Yes
- Repair the excessive resistance in the Generator Case Ground.
- Perform the PCM Verification TestPCM Verification Test
No
- Go to 4
4. (K20) GEN FIELD CONTROL CIRCUIT SHORTED TO VOLTAGE
1. Turn the ignition off.
2. Disconnect the Generator harness connector.
3. Disconnect the Powertrain Control Module (PCM) harness connector.
4. Turn the ignition on.
5. Measure the voltage of the (K20) Gen Field Control circuit.
Is there any voltage present?
Yes
- Repair the (K20) Gen Field Control circuit for a short to voltage.
- Perform the PCM Verification TestPCM Verification Test
No
- Go to 5
5. (K20) GEN FIELD CONTROL CIRCUIT SHORTED TO GROUND
1. Turn the ignition off.
2. Measure the resistance between ground and the (K20) Gen Field Control circuit in the Generator harness connector.
Is the resistance below 100 ohms?
Yes
- Repair the short to ground in the (K20) Gen Field Control circuit.
- Perform the PCM Verification TestPCM Verification Test
No
- Go to 6
6. (K20) GEN FIELD CONTROL CIRCUIT OPEN OR HIGH RESISTANCE
1. Measure the resistance of the (K20) Gen Field Control circuit between the Generator harness connector and the Powertrain Control Module (PCM) harness connector.
Is the resistance below 5.0 ohms?
Yes
- Go to 7
No
- Repair the open in the (K20) Gen Field Control circuit.
- Perform the PCM Verification TestPCM Verification Test
7. (A804) GEN SENSE CIRCUIT OPEN OR HIGH RESISTANCE
1. Measure the resistance of the (A804) Gen Sense between the Generator harness connector and the Powertrain Control Module (PCM) harness connector.
Is the resistance below 5.0 ohms?
Yes
- Go to 8
No
- Repair the (A804) Gen Sense circuit for an open circuit or high resistance.
- Perform the PCM Verification TestPCM Verification Test
8. GENERATOR
1. Turn the ignition off.
2. Connect the Powertrain Control Module (PCM) harness connector.
3. Turn the ignition on.
4. With a scan tool, actuate the Generator Field to toggle on and off.
5. Using a 12-volt test light connected to ground, check the (K20) Gen Field Control in the Generator harness connector.
NOTE: The test light should be illuminated and bright when toggled on. Compare the brightness to that of a direct connection to the battery.
Does the test light toggle on and off correctly during the actuator test?
Yes
- Replace the Generator.
- Perform the PCM Verification TestPCM Verification Test
No
- Go to 9
9. POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Generator and the Powertrain Control Module (PCM).
2. Look for any chafed, pierced, pinched, or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals.
4. Monitor the scan tool data relative to this circuit and wiggle test the wiring and connectors.
5. Look for the data to change or for the DTC to reset during the wiggle test.
6. Search for any Technical Service Bulletins that may apply.
Were any problems found?
Yes
- Repair as necessary.
- Perform the PCM Verification TestPCM Verification Test.
No
- Replace and program the Powertrain Control Module (PCM).
- Perform the PCM Verification TestPCM Verification Test.