Code 16, OPTI-Spark Ignition System Low Resolution Pulse: Notes

Ignition system supplies 2 timing inputs to PCM, a high resolution signal (360 pulses per camshaft revolution) and a low resolution signal (4 pulses per camshaft revolution). PCM can determine if either timing input is not being received by comparing inputs. If PCM detects high resolution pulse without detecting low pulse, Code 16 will set. Reference signal on resolution line toggles between zero and 5 volts as camshaft turns.

1. If engine starts at this time, code is intermittent.
2. This step determines if PCM is sending out a signal to distributor for processing. If this signal is not available or is shorted to ground or voltage, distributor cannot ground it to produce reference pulses.
3. If Code 41 and/or 42 is also set with Code 16 and no external fault can be found, replace PCM. If only Code 16 is set and distributor connections are okay, replace distributor.