Circuit/System Testing
- Measure the voltage at the battery terminals and compare it with the scan tool ECM Ignition 1 signal parameter. Verify that battery and Ignition 1 signal readings do not differ more than 1.0 volt.
- If greater than the specified value, test the Ignition 1 and ground circuits of the ECM for an open/high resistance. If the circuits test normal replace the ECM.
- Go to CHARGING SYSTEM TEST .