Chart 2 of 3 - Ignition

Diagnostic Chart 2:

Schematic:

The ECM controls spark timing and dwell (spark On-time) under all engine running conditions. Each of the two electronic ignition (EI) modules has the ability to charge and discharge each of its three primary coils independently based on ECM control. The ECM uses a high control signal of near 5 volts to charge up the primary coil and a low control signal of near 0 volts to discharge the primary coil. If the primary coil is charged and the control signal is low, current will be induced in the secondary coil and will fire out of its secondary tower.

DIAGNOSTIC AIDS

IMPORTANT: If the camshaft sensor signal is missing, the ECM will provide spark to both mating cylinders as well as default to non-sequential fuel injection. The engine will start if the condition occurs.

Use Scan tool to perform an IGNITION COIL test for each individual cylinder while listening closely for spark at appropriate ignition coil.

Spark on one cylinder of the 1, 3, 5 bank and spark on another cylinder of the 2, 4, 6 bank indicates that each EI module power and ground circuits are OK.