Electronic Ignition (EI) System Diagnosis

Electronic Ignition System Diagnosis

Circuit Description

The Electronic Ignition (EI) System uses a waste spark method of spark distribution. The crankshaft position (CKP) sensor sends reference pulses to the engine control module (ECM). The ECM then triggers the EI system ignition coil. Once the ECM triggers the ignition coil, both of the connected spark plugs ignite at the same time. One cylinder is on its compression stroke at the same time that the other is on the exhaust stroke, resulting in lower energy needed to ignite the spark plug in the cylinder on its exhaust stroke. This leaves the remainder of the high voltage to be used to ignite the spark plug in the cylinder on its compression stroke. The ignition coil consists of the following circuits:

* The ignition 1 voltage
* The ignition control 1 and 4
* The ignition control 2 and 3

Test Description

The numbers below refer to the step numbers on the diagnostic table.
4. This step tests for a short to ground in the ignition 1 voltage circuit.
5. This step tests for a fault in the ignition 1 voltage circuit. It is necessary to command the fuel pump relay ON, because the fuel pump relay supplies the voltage to the ignition coil.

6. This step tests for high resistance. Three ohms or more can cause can cause a driveability condition.