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

Optical/Fuel Temperature Sensor:

DESCRIPTION
The optical sensor sends what is called a High Resolution Signal and a Pump Cam signal to the PCM. There is a harness filter inline to the Optical/Fuel temperature sensor which is used in order to filter the shared 5 volt reference signal.

High Resolution Signal (256X)
The high resolution signal is an optical device which generates 64 equally spaced pulses per cylinder combustion stroke from the slotted disc mounted on the injection pump timing cam ring. The pulses are counted by the PCM and used to measure the angular pump displacement. Fuel is metered by using the angular indication and timing is measured by counting the angular pulses between the pump cam signal and the crankshaft position sensor signal.