Powertrain Controls - ECM/PCM

DTC 16 Chart Distributor Igntion System:

Distributor Ignition System Wiring Diagram:

Circuit Description:

The distributor ignition system supplies two timing inputs to the ECM, a high resolution signal (360 pulses per one crankshaft revolution) and a low resolution signal (4 pulses per one crankshaft revolution). The ECM can determine if one of the timing inputs is not being received by comparing the two inputs. If the ECM detects the high resolution timing pulse without detecting the low resolution timing pulse, this DTC will set.

The reference signals toggle between 0 and 5 volts as the camshaft turns. Therefore, an open, a short to voltage, a short to ground, or a defective sensor inside the distributor can prevent the voltage from pulsing at the ECM.

Test Description: Number(s) below refer to circled number(s) on the diagnostic chart.

1. DTC 16 will set if:

- 720 high resolution timing pulses occur before any low resolution pulses are detected.

2. This test will determine if the ECM is sending out a signal to the distributor for processing. If this signal is not available or is shorted to ground or voltage, the distributor cannot ground it to produce reference pulses.

Diagnostic Aids:

If DTC 16 does not reset and the vehicle still does not start, Related Tests, Information and Procedures