Circuit/System Testing
- If DTC 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 1 fuse in the underhood fuse block.
- If the ignition 1 voltage is not present on either test point of the ECM 1 fuse, then replace underhood fuse block.
- If the ignition 1 voltage is present on one test point of the ECM 1 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 1 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.