Powertrain Controls - ECM/PCM

Diagnostic Trouble Code (DTC) 36:

Distributor Ignition System Circuit:

CIRCUIT DESCRIPTION
The distributor ignition system supplies two timing inputs to the Powertrain Control Module (PCM), a high resolution signal (180 pulses per one crankshaft revolution) and a low resolution signal (4 pulses per one crankshaft revolution). The PCM can determine if one of the timing inputs is not being received by comparing the two inputs. If the PCM detects the low resolution timing pulse without detecting the high resolution timing pulse, this Diagnostic Trouble Code (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 PCM.

DTC 36 WILL SET WHEN
40 low resolution pulses occur before any high resolution pulses are detected.

ACTION TAKEN (PCM DEFAULT)
The Malfunction Indicator Lamp (MIL) will illuminate.

DTC CHART TEST DESCRIPTION
Numbers below refer to circled numbers on the diagnostic chart.

1. This determines if the DTC 36 is intermittent.

2. This test will determine if the PCM 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.

3. If a DTC 41 and/or 42 is also set with a DTC 36, and no external fault can be found, replace the PCM. If only DTC 36 is set and distributor connections are OK, replace distributor.

DIAGNOSTIC AIDS
The engine does not need the high resolution pulse to operate. If a DTC 36 is present and the vehicle will not start, check for DTC 16 and use that chart first. If the engine will still not run, refer to Chart A-3 Engine Cranks But Won't Run. Related Tests, Information and Procedures

If distributor components must be replaced, check distributor vent system (if so equipped). Refer to Chart C-4C Distributor Vent System Check. Chart C-4C Distributor Vent System Check

When an intermittent DTC 36 occurs, a misfire may be apparent. To locate an intermittent, use the Tech 1 scanner's snapshot feature and try to duplicate the condition under which the misfire is present. When reviewing the captured data, watch for any abnormal high and low resolution timing pulses. Refer to Diagnosis By Symptom/Cuts Out, Misses. Cuts Out/Misses