P2509 OBD II Trouble Code ECM/PCM Power Input Signal Intermittent Code Dodge

Full details on why you get a P2509 ECM power input signal trouble code, how to diagnose it, along with potential symptoms and causes.

Symptoms of P2509 OBD II Trouble Code

  • Malfunction Indicator Lamp (MIL) illumination with P2509 DTC set
  • Hard to start or failure to start
  • Tachometer may fluctuate between 500 to 700 rpm when idling cold
  • Check gauges light may illuminate and voltmeter displays 11 volts or less
  • Truck may cut off while driving
  • Additional codes P2502 - charging system error and P2503 - charging system output low may accompany the code P2509

Common Causes of P2509 OBD II Trouble Code

  • Battery failure
  • Poor connection at the batteries
  • Alternator is either overcharging or undercharging
  • Large voltage drop through loose or corroded cables
  • Electrical clutch fan short to ground
  • Bad connection at ECM
  • Leaking diode
  • Battery + positive shorted to ground or other circuits
  • Open or return ground circuit