P2503
P2503-CHARGING SYSTEM OUTPUT LOW
For a complete wiring diagram, refer to the Wiring Information. Electrical Diagrams
- When Monitored:
With the ignition on. Engine RPM greater than 1000 RPM. With no other charging system codes set.
- Set Condition:
Battery voltage is 1 volt greater than desired voltage for more than 10 seconds. Battery voltage greater than 15.75 volts. One Trip Fault.
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. Start the engine and allow it to reach operating temperature.
WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hand near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in possible serious or fatal injury.
2. 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. CHARGING SYSTEM OPERATION
1. Perform the diagnostic procedure for CHECKING THE CHARGING SYSTEM OPERATION. Checking the Charging System Operation.
Were any problems found?
Yes
- Repair as necessary.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.
No
- Got To 3
3. (A804) GEN SENSE CIRCUIT OPEN OR HIGH RESISTANCE
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 the PCM Pinout Box 8815 to perform diagnosis.
1. Turn the ignition off.
2. Disconnect the Generator harness connector.
3. Disconnect the C1 and C2 Powertrain Control Module (PCM) harness connectors.
4. Measure the resistance of the (A804) Gen Sense circuit between the Generator harness connector and the appropriate terminal of special tool #8815.
Is the resistance below 5.0 ohms?
Yes
- Go To 4
No
- Repair the (A804) Gen Sense circuit for an open circuit or high resistance.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.
4. (K20) GEN FIELD CONTROL CIRCUIT SHORTED TO VOLTAGE
1. Turn the ignition on.
2. Measure the voltage of the (K20) Gen Field Control circuit in the Generator harness connector.
Is there any voltage present?
Yes
- Repair the (K20) Gen Field Control circuit for a short to voltage.
- Perform the PCM VERIFICATION TEST. PCM 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 above 100 ohms?
Yes
- Go To 6
No
- Repair the (K20) Gen Field Control circuit for a short to ground.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.
6. (K20) GEN FIELD CONTROL CIRCUIT OPEN OR HIGH RESISTANCE
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 the PCM Pinout Box 8815 to perform diagnosis.
1. Measure the resistance of the (K20) Gen Field Control circuit between the Generator harness connector and the appropriate terminal of special tool #8815.
Is the resistance below 5.0 ohms?
Yes
- Go To 7
No
- Repair the (K20) Gen Field Control circuit for an open circuit or high resistance.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.
7. GENERATOR
1. Connect the C1 and C2 Powertrain Control Module (PCM) harness connectors.
2. Turn the ignition on.
3. Connect a 12-volt test light between the (A804) Gen Sense circuit and the (K20) Gen Field Control circuit in the Generator harness connector.
4. With the scan tool, actuate the Alternator Field Control State.
NOTE: The voltage supplied to the solenoid circuit during the actuation will be less than battery voltage. The test light should be illuminated, but not as bright as a direct connection to the battery.
Is the test light illuminated during the actuation?
Yes
- Replace the Generator.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.
No
- Go To 8
8. 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. Search for any Technical Service Bulletins that may apply.
Were any problems found?
Yes
- Repair as necessary.
- Perform the PCM VERIFICATION TEST. PCM Verification Test.
No
- Replace and program the Powertrain Control Module (PCM).
- Perform the PCM VERIFICATION TEST. PCM Verification Test.