Circuit/System Testing

WARNING: This page is about a different variant/trim than selected.

If DTCs P0685, P0689, or P0690 are set, test and repair those DTCs first.
With the ignition ON, and the engine OFF, test for ignition 1 voltage at both test points of the ECM IGN fuse in the underhood fuse block.
IMPORTANT: The ignition main relay that is shown on the electrical wiring schematic is not serviceable. It is soldered to the bus bar, internal to the underhood fuse block. If it is determined that the ignition main relay is not functioning correctly, the underhood fuse block must be replaced.
- If the ignition 1 voltage is not present on either test point of the ECM IGN fuse, then replace underhood fuse block.
- If the ignition 1 voltage is present on one test point of the ECM IGN fuse, then repair the short to ground in the ignition 1 voltage circuit to the electronic control module (ECM). If the wire circuit tests normal, then replace the ECM.
- If the ignition 1 voltage is present on both test points of the ECM IGN fuse, then inspect and test for loose and corroded terminals at the underhood fuse block electrical connector, and the ECM electrical connectors, which contains the ignition 1 voltage circuit. If the electrical connectors test normal, then repair the ignition 1 voltage circuit, for an open or high resistance. All wire circuit resistance should measure 2 ohms or less. If the wire circuit tests normal, then replace the ECM.