1. Verify that the following DTCs are not set: U1814, B1428.
锟斤拷 If either of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle (See: Diagnostic Trouble Code
Descriptions/Diagnostic Trouble Code (DTC) List - Vehicle).
2. With a scan tool, access BCM, Power Mode data display list and compare all parameters listed with the corresponding ignition key position.
The PMM Power Mode Parameters table below illustrates the correct state of these input parameters (circuits) in correspondence to the
ignition switch position. The circuits which the individual parameters are related to are in parentheses.
Note: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
1. Inspect for an open B+ fuse. The fuse should be OK.
锟斤拷 If the fuse is open, test the following circuits for a short to ground, if all circuits test OK, replace the BCM.
* B+ to the ignition switch
* Accessory voltage
* Off/Run/Crank voltage
* Ignition 1 voltage
* Accessory wakeup serial data (BCM output)
* Run/crank ignition 1 voltage (BCM output)
2. Disconnect the harness connector at the ignition switch.
3. Verify that a test lamp illuminates between the B+ circuit terminal 4 and ground.
锟斤拷 If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
Note: The ignition switch component test must be preformed before proceeding with this test to verify the integrity of the switch.
4. Perform the ignition switch component test. The test should pass.
锟斤拷 If the ignition switch fails, replace the ignition switch.
5. Ignition OFF, disconnect the X1 harness connector at the BCM, test for less than 1.0 volt between the following circuit terminals of the BCM
* Ignition key resistor signal terminal 4
* Off/Run/Crank voltage terminal 2
* Accessory voltage terminal 21
* Ignition 1 voltage terminal 14
锟斤拷 If greater than specified, test the circuit for a short to voltage.
6. Test for less than 1.0 ohm of resistance between the BCM and the ignition switch on the following circuit terminals.
* Ignition key resistor signal, BCM terminal 4 and ignition switch terminal 6
* Off/Run/Crank voltage, BCM terminal 2 and ignition switch terminal 5
* Accessory voltage, BCM terminal 21 and ignition switch terminal 3
* Ignition 1 voltage, BCM terminal 14 and ignition switch terminal 2
锟斤拷 If greater than specified, repair the circuit for open/high resistance
7. Test for infinite resistance between the ignition key resistor signal circuit terminal 4 of the BCM and ground.