Reference Information
Schematic Reference
* Body Control System Schematics (See: Body and Frame/Body Control Systems/Diagrams/Electrical Diagrams)
* Power Distribution Schematics (See: Diagrams/Electrical Diagrams/Starting and Charging/Power and Ground Distribution/System
Diagram/Power Distribution Schematics)
Connector End View Reference
Component Connector End Views (See: Diagrams/Connector Views)
Description and Operation
Power Mode Description and Operation (See: Power and Ground Distribution/Description and Operation/Power Mode Description and Operation)
Electrical Information Reference
* Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Circuit
Testing/Circuit Testing)
* Connector Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Connector Repairs/Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (See: Testing and Inspection/Component Tests and General Diagnostics/General
Electrical Diagnostic Procedures/Circuit Testing/Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Wiring
Repairs/Wiring Repairs)
Scan Tool Reference
Control Module References (See: Testing and Inspection/Programming and Relearning) for scan tool information
Circuit/System Verification
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 Body Control Module, 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.
Circuit/System Testing
Note: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
1. Inspect for an B+ fuse to the ignition switch. 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+
* 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.
