Engine Control System

DIAGNOSTIC CHART

Diagnostic Chart:

Diagnosis
No signal entered from camshaft position sensor, but signal entered from crankshaft position sensor.
Harness connector between ECM and camshaft position sensor is shorted or open.

Trouble Symptom
Engine stalls, engine will not start.

CHECK INPUT SIGNAL FOR ECM

Input Test:

1. Set the positive probe and earth lead of oscilloscope at ECM connector terminals (E30) No. 8 - (E30) No. 9.

Oscilloscope Pattern:

2. Measure signal voltage indicated on oscilloscope while cranking engine.

CHECK HARNESS CONNECTOR BETWEEN ECM AND CAMSHAFT POSITION SENSOR

Harness Test:

1. Turn ignition OFF.
2. Unplug connectors from ECM and camshaft position sensor.
3. Measure resistance of harness connector between ECM and camshaft position sensor.

Connector & Terminal Resistance
(E30) 8 - (E19) 1 10 ohms max.
(E30) 9 - (E19) 2 10 ohms max.

Harness Test:

4. Measure resistance of harness connector between ECM and body to make sure there is not a short.

Connector & Terminal Resistance
(E30) 8 - body 1 M ohm min.
(E30) 9 - body 1 M ohm min.
(E30) 11 - body 1 M ohm min.

CHECK CRANKSHAFT POSITION SENSOR

Sensor Test:

1. Remove camshaft position sensor.
2. Set the positive probe at sensor connector terminal No. 1 and set the earth lead at terminal No. 2.
3. Check that a wave profile appears crossing a magnet near the pick-up coil of the camshaft position sensor.