Circuit/System Testing

With the ignition OFF, disconnect C306.
Connect a 3-amp fused jumper wire between the signal circuit of the fuel level sensor and the low reference circuit of the fuel level sensor on the male terminal side of the connector.
With the ignition ON, install a scan tool and observe the Fuel Tank Level Remaining parameter in the ECM EVAP Data List.

If the Fuel Tank Level Remaining parameter indicates a value less than 98 percent, check the signal circuit and the low reference circuit of the fuel level sensor for an open, a high resistance or a short to voltage.

If both the signal circuit and the low reference circuit tests normal, replace the ECM.

If the Fuel Tank Level Remaining parameter indicates a value greater than 98 percent, check the signal circuit and the low reference circuit of the fuel level sensor for an open, for a high resistance or a short to voltage between C306 and the fuel level sensor.

If both the signal circuit and the low reference circuit tests normal between C306 and the fuel level sensor, replace the fuel level sensor.