Circuit/System Testing

WARNING: This page is about a different car, the 2011 GMC Yukon, 2011 Chevrolet Tahoe, and 2011 Cadillac Escalade. However, it is still accessible from the selected car via links, so may be relevant.

Ignition OFF, open the hood to disable the Auto-Stop function. Refer to Hybrid Modes of Operation Description .
Ignition ON, verify the scan tool hood position parameter displays Open.
- If the hood position does not display Open, refer to Diagnostic Trouble Code (DTC) List - Vehicle for DTC P254F.
Ignition OFF for 1 minute, disconnect the harness connector at the ignition coil.
Ignition OFF, all vehicle systems OFF, this may take up to 2 minutes, test for less than 5 Ω between the ground circuit terminal B and ground.
- If greater than the specified range, repair the ground circuit for an open/high resistance.
Test for less than 5 Ω between the low reference circuit terminal C and ground.
- If greater than the specified range, test the circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
Test for less than 2 between the ignition voltage circuit terminal A and the fuse.
- If greater than the specified range, repair the ignition voltage circuit for high resistance.
Ignition ON, verify that a test lamp illuminates between the ignition voltage circuit terminal A and ground.
- If the test lamp does not illuminate, test the ignition voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition voltage circuit fuse is open, test all components connected to the ignition voltage circuit and replace as necessary.
If all circuits test normal, test or replace the ignition coil assembly.