Chart C-4A Distributor Ignition System Check

Chart C-4A:

Chart C-4A: Distributor Ignition (DI) System Check:

Distributor Ignition System Circuit:

CIRCUIT DESCRIPTION
Numbers below refer to circled numbers on the diagnostic chart.

The battery should be fully charged prior to any tests.

1. To disconnect the tachometer lead, it will be necessary to disconnect the gray ignition coil connector from the ignition coil and jumper the "B" terminal of the harness connector to the "B" terminal of the ignition coil using a fused jumper and terminal test adapter kit J 35616-A.

Checks for proper output from the distributor ignition system. The spark tester requires a minimum of 25,000 volts to fire. This check can be used in case of an ignition miss, because the system may provide enough voltage to run the engine but not enough to fire a spark plug under heavy load.

2. This test will separate the distributor cap, rotor and ignition wires from the ignition coil to help identify a secondary ignition system problem. It is necessary to unscrew the top terminal on the ST 125 spark tester for a proper fit in the distributor end of the coil wire.

3. This will determine if the proper available voltage exists in the primary ignition circuit.

4. This check will begin to determine if the Powertrain Control Module (PCM) is providing a signal to the ignition coil module or not. If the PCM is not providing a signal to the ignition coil module, the problem exists between the distributor and PCM.

5. A grounded coil circuit will cause the ignition fuse to open, and a no-start condition will occur.

DIAGNOSTIC AIDS
An ignition coil wire that is open or shorted to ground can cause a no start condition.