Diesel Fuel Temperature / Fuel Pump Position Combination Sensor: Description and Operation

Figure 3-15: Optical/Fuel Temperature Sensor Circuit:

Optical/Fuel Temperature Sensor Tests
The optical/fuel temperature sensor supplies three signals to the PCM for fuel control and timing. A high resolution signal helps determine injection timing and fuel control. A pump cam signal provides reference pulses that monitor and help determine injection timing. The fuel temperature signal helps the PCM determine pump advance or retard requirements and fuel flow. The sensor is located at the top of the injection pump adjacent to the fuel shut-off solenoid.

A fault in the optical sensor or related wiring will produce fast idle and performance problems. A problem will cause a high resolution circuit fault, or a cam reference pulse error fault.

The sensor can be checked with a scan tool.