Powertrain Controls - ECM/PCM

DTC 36 Chart:

Ignition Reference (24X Signal) Circuit:

Circuit Description:
The 24X Crankshaft Position (CKP) sensor is used to improve idle spark control at low engine speeds. The 24X CKP sensor is located behind the harmonic balancer on the front of the engine where it picks up pulses from a reluctor wheel on the crankshaft. Its signal is conditioned by the PCM and used to more accurately control spark at lower engine speeds up to approximately 2000 RPM.

DTC 36 Will Set When:
The PCM determines that 6 or more consecutive 24X crankshaft position sensor reference pulses have not occurred. This test is executed once per ignition key cycle immediately after start-up.

Action Taken (PCM will default to):
The PCM will disregard the 24X sensor input and base timing from the 3X low resolution CKP sensor. The MIL will not become illuminated.

DTC 36 Will Clear When:
A current DTC 36 will clear after each ignition key cycle. A history DTC 36 will clear after 50 consecutive ignition key cycles without a current DTC 36 being stored.

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

1. The 24X signal RPM should be the same as engine speed up to approximately 2000 RPM at which time it stops. This test determines if the PCM is putting out a 24X signal.

2. This test determines if signal voltage is present up to the PCM.

3. This will determine if B+ is present at the sensor input.

4. By applying B+ to the 24X crankshaft sensor pigtail circuit, pigtail and sensor integrity can be determined.

5. Ground path continuity is determined with this test.

Diagnostic Aids:
An intermittent 24X signal error can be caused by poor connections. Ignition feed, reference low and the signal circuits should all be checked for poor connections.