Powertrain Controls - ECM/PCM

DTC 17 Chart:

Camshaft Position Sensor Circuit:

Circuit Description:
The camshaft position sensor is a "Hall-Effect" switch, located on the front of the engine. The camshaft position sensor sends a signal to the PCM when the #1 cylinder is on the intake stroke. This signal is used by the PCM to synchronize Sequential Fuel Injection (SFI) mode of operation with each intake valve opening. If the cam reference signal is not received by the PCM, the PCM will still pulse the fuel injectors sequentially, but the fuel injectors may not be in synch with each intake valve opening. That is, fuel injector timing may not be as accurate because the PCM does not know the exact time each intake valve is opening. A loss of this signal or extra (false) cam reference signals, above 500 RPM, will set a DTC 17.

DTC 17 Will Set When:
Cam reference pulses are not detected by the PCM for 3 seconds while the engine is running, or CAM pulse is missing on the first pass through the internal PCM self test of the camshaft position sensor.

Action Taken (PCM will default to):
The PCM will pulse the injectors sequentially though possibly not in the correct sequence. The malfunction indicator lamp will not be illuminated.

DTC 17 Will Clear When:
A current DTC 17 will clear when the cam signal begins to toggle. A history DTC 17 will clear after 50 consecutive ignition key cycles without a current DTC 17 being stored.

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

1. The PCM performs a test for DTC 17 when the engine is running or during cranking.

2. By repeatedly "bumping" the starter, the camshaft timing mark and the camshaft position sensor will align with each other. At this point, the voltage from the sensor applied to the PCM should drop to near zero temporarily. This indicates that the camshaft position sensor is capable of sending a signal to the PCM.

3. Before replacing the camshaft position sensor, inspect the sensor for proper installation.

Diagnostic Aids:
An intermittent cam reference signal can be caused by poor connections, cracked sensor or internal engine problem.