Power Mode Mismatch
Power Mode Mismatch
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview)provides an overview of each diagnostic category.
Circuit/System Description
The body control module (BCM) monitors the ignition inputs Ignition Off/Run/Crank, Ignition 1 Run/Crank and the Ignition Accessory signals supplied from the ignition switch. The BCM uses the sequence that the signals appear, their voltage levels and the engine run flag (ERF) status to determine the power mode. Battery voltage is supplied to the ignition switch by the BATT IGN SWITCH fuse. The BCM provides a 5-volt supply voltage to the ignition switch then back to the BCM. The table below shows the correct ignition switch inputs and power modes.
Diagnostic Aids
The power modes and controls are determined using BCM logic. Comparing the parameters in each ignition switch position to the Ignition Switch Inputs and Power Modes table will determine if there is a power mode fault.
Reference Information
Description and Operation
Power Mode Description and Operation (Power Mode Description and Operation)
Scan Tool Reference
Control Module References (Programming and Relearning)for Scan Tool Information
Circuit/System Verification
1. Verify that the following DTCs are not set:
* B1372
* B1373
* B1382
* B1383
* B1442
* B1443
• If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle (Diagnostic Trouble Code Descriptions) .
2. With a scan tool, compare all parameters listed with the Ignition Switch Inputs and Power Modes table. Verify that all parameters listed are correct in correspondence with the ignition switch position listed:
If any parameter is incorrect and none of the DTCs listed are set, replace the BCM.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the repair.
Control Module References (Programming and Relearning) for module replacement, setup, and programming