C 1500 Truck 2WD V8-6.5L DSL Turbo VIN F (1998)
Optical/Fuel Temperature Sensor: Description and Operation
Optical Sensor (s)
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.
DESCRIPTION
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.
Injection Pump Cam Signal (4X)
The Pump Cam signal is an optical device which generates one pulse per cylinder combustion stroke from a slotted disc mounted on the injection
pump timing cam ring. The pulse is used to located the start of injection event for each cylinder (i.e. timing) with the respect to the crankshaft position
sensor. The number one cylinder is identified with a wider pulse (larger slot in disc). The PCM uses this information to adjust idle fuel, timing, trigger
real time events and is used in the diagnostics of crankshaft position sensor and the high resolution circuit.
