For further Diagnosis and Testing of the Engine Concentrated Control System (ECCS) refer to Chapter 4 or 5 in this guide. Additional distributor and ignition coil information can be found in Chapter 3 of this guide.
CRANK ANGLE SENSOR
When the ignition is ON and the main ECCS relay is activated, 12 volts is sent to the crank angle sensor LED. When a slit uncovers the photo diode and it detects the light, a 5 volt signal is sent to the ECU. The unit is easy to test but it must be removed from the engine. Refer to to test procedure below.
- First test the circuit to the sensor. Unplug the sensor connector, turn the ignition ON and check for 12 volts between one of the terminals and ground. The other terminals are return signals to the ECU, do not use them for voltmeter ground.
- Turn the ignition OFF , remove the distributor assembly and reconnect the plug to the crank angle sensor. Peel back the insulation sufficiently to connect a voltmeter to the wires. Ground the coil high tension wire.
- With the voltmeter connected to a good chassis ground, turn the ignition ON and slowly rotate the distributor. One of the return signal wires should have 5 volts off and on with each degree of rotation. The other should have 5 volts off and on with each 180 degrees (4 cyl.) or 120 degrees (6 cyl.) of rotation.
- Visually check the rotor plate for rust or damage.