ESA Ignition Circuit System

Ignition Signal Circuit:

Code 41 Wiring Diagram:

CIRCUIT DESCRIPTION:

The ECM receives a signal from the ignition coil. The ECM uses a driver to cause the coil to spark to the distributor. This is done by a driver that turns 12 volts from the coil to less than 1.0 volt. When this happens the ECM looks for a signal. If this signal is not present for more than 2 seconds, while cranking, Code 41 will set. If a Code 42 is present at the same time, repair that code first.

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

1. This will simulate a crank signal to the ECM. The ECM will then ground the ignition coil to create spark.

2. Check voltage supply to coil.

3. Look for the low voltage on ignition coil. The noise suppressor could be shorted to ground.

4. Check to see if ECM in the short to ground in BROWN/WHITE wire.

5. High resistance in the coil could cause a low voltage.

DIAGNOSTIC AIDS:

An intermittent may be caused by a poor connection rubbed through wire insulation or a wire broken inside the insulation. Inspect ECM harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection and damaged harness.