DTC P0462: Fuel Level Sending Unit Volts Too Low: Testing

Turn ignition on, engine not running. With the DRBIII®, read the fuel level sensor voltage. Is the fuel level sensor voltage below 0.2 volt? If yes, go to next step. If no, go to INTERMITTENT CONDITION under SELF-DIAGNOSTIC SYSTEM.
Turn the ignition off. Disconnect the Fuel Pump Module harness connector. Fuel pump module is mounted in top of fuel tank. Turn ignition on, engine not running. With the DRBIII®, read the Fuel Level Sensor voltage. Did the Fuel Level Sensor voltage change from below 0.2 volt to above 4.0 volts? If yes, replace the fuel level sensor. Fuel level sensor is located on fuel pump module and can be replaced separately. See FUEL LEVEL SENSOR under SENSORS & SWITCHES in REMOVAL & INSTALLATION - GRAND CHEROKEE article. If no, go to next step.
Turn the ignition off. Disconnect PCM harness connectors. Check connectors and clean/repair as necessary. Measure the resistance between ground and the Fuel Level Sensor Signal circuit at Fuel Pump Module harness connector. Is the resistance below 100 ohms? If yes, repair the fuel level sensor signal circuit for a short to ground. If no, go to next step.
Ensure fuel pump module and the PCM are disconnected. Measure the resistance between the (K226) Fuel Level Sensor Signal circuit and the (K4) Sensor ground circuit at the fuel pump module harness connector. Is the resistance below 5.0 ohms? If yes, repair the (K226) Fuel Level Sensor Signal circuit for a short to the (K4) Sensor ground circuit. If no, go to next step.

NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.

Using the wiring diagram as a guide, inspect the wire harness connectors. Pay particular attention to all power and ground circuits. If there are no possible causes remaining, replace PCM. Program the new PCM. See PROGRAMMING .