P2503 Possible Causes
- Faulty generator (alternator)
- Generator wiring harness is open or shorted
- Poor electrical connection in the generator circuit
- Faulty Powertrain Control Module (PCM)
How to Fix Code P2503
Check the “Possible Causes” listed above. Visually inspect the wiring harness and related connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.
Possible Symptoms
Engine light on (or service engine soon warning light)
P2503 Meaning
The Powertrain Control Module (PCM) monitors the charging system for output voltage variations. The PCM sets the OBDII code P2503 when the output voltage is outside factory specifications.