DTC 17 - High Resolution Circuit Fault: Notes

The optical sensor provides a high resolution signal to the PCM by counting pulses on the sensor disk located in the injection pump. The high resolution signal is one of the most important inputs used by the PCM for fuel control and timing. DTC 17 will set when 8 pump cam reference pulses occur without an increase in high resolution counts (internal to PCM). PCM will default to backup fuel.

1. This step determines if a 5-volt reference is present.
2. This step checks the ground circuit.
3. This step checks if the sensor is sending a signal back to the PCM.