P2503
P2503-CHARGING SYSTEM OUTPUT LOW
- When Monitored:
The engine running. The engine speed greater than 1157 RPM.
- Set Condition:
The battery sensed voltage is 1 volt below the charging goal for 13.47 seconds. The Powertrain Control Module (PCM) senses the battery voltage turns off the field driver and senses the battery voltage again. If the voltages are the same, the code sets. 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. ACTIVE DTC
NOTE: Inspect the vehicle for aftermarket accessories that may exceed the Generator System output.
1. Ignition on, engine not running.
NOTE: The battery must be fully charged.
NOTE: The Generator belt tension and condition must be checked before continuing.
2. With a scan tool, read the DTCs.
3. With a scan tool, erase the DTCs.
4. Start the engine.
5. Allow the idle to stabilize.
6. With the scan tool, read the DTCs.
Is the DTC active at this time?
Yes
- Go To 2
No
- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition 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 may result in possible serious or fatal injury.
1. Ignition on, engine not running.
NOTE: Make sure all wires are clear of the engines moving parts.
2. Measure the voltage between the Generator B+ Output Terminal and the Battery+ Post.
3. Start the engine.
Is the voltage above 0.1 of a volt?
Yes
- Repair the excessive resistance in the battery positive circuit between the Generator and Battery.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- 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 may result in possible serious or fatal injury.
1. Start the engine.
2. Warm the engine to operating temperature.
NOTE: Make sure all wires are clear of the engines moving parts.
3. Measure the voltage between the Generator Case and Battery ground post.
Is the voltage above 0.1 of a volt?
Yes
- Repair the excessive resistance in the Generator Case Ground.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Go To 4
4. (A803/A804) GEN SENSE CIRCUIT OPEN
1. Turn the ignition off.
2. Disconnect the PCM harness connector.
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 PCM Pinout Box 8815 to perform diagnosis.
3. Measure the voltage of the (A803/A804) Gen Sense circuit in the appropriate terminal of the PCM Pinout Box 8815.
Is the voltage equal to Battery voltage?
Yes
- Go To 5
No
- Check the (A803/A804) Gen Sense Circuit for an open. If OK, replace the Generator.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
5. GENERATOR OPERATION
1. Turn the ignition off.
2. Disconnect the Generator Field harness connector.
3. Using a 12-volt test light connected to ground, probe the Gen Field Control circuit in the Generator Field harness connector.
4. Ignition on, engine not running.
5. With a scan tool, actuate the Alternator Field Duty Cycle.
Does the test light illuminate brightly and flash on and off?
Yes
- Replace the Generator.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Go To 6
6. (K20) GEN FIELD CONTROL CIRCUIT SHORTED TO BATTERY VOLTAGE
1. Turn the ignition off.
2. Disconnect the PCM harness connectors.
3. Ignition on, engine not running.
4. Measure the voltage on the (K20) Gen Field Control circuit in the Generator Field harness connector.
Is the voltage above 1.0 volt?
Yes
- Repair the short to battery voltage in the (K20) Gen Field Control circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Go To 7
7. (K20) FIELD CONTROL CIRCUIT OPEN
1. Turn the ignition off.
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 PCM Pinout Box 8815 to perform diagnosis.
2. Measure the resistance of the (K20) Gen Field Control circuit from the Generator Field harness connector to the appropriate terminal of the PCM Pinout Box 8815.
Is the resistance below 5.0 Ohms?
Yes
- Go To 8
No
- Repair the open in the (K20) Gen Field Control circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
8. (K20) GEN FIELD CONTROL CIRCUIT SHORTED TO GROUND
1. Measure the resistance between ground and the (K20) Gen Field Control circuit in the Generator Field harness connector.
Is the resistance below 100 Ohms?
Yes
- Repair the short to ground in the (K20) Gen Field Control circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Go To 9
9. POWERTRAIN CONTROL MODULE (PCM)
NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage or terminal push out. Repair as necessary.
1. Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.
Were there any problems found?
Yes
- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Replace and program the Powertrain Control Module.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.