Power Mode Mismatch
Power Mode Mismatch
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.
DTC Descriptors
DTC B1370
- Device Ignition 1 (ON and START) Circuit
DTC B1380
- Device Ignition ACCESSORY Circuit
DTC B1440
- Power Mode Master Input Circuits Mismatch
DTC B1441
- Device Ignition OFF, RUN, and CRANK Circuit
Diagnostic Fault Information
Circuit/System Description
The vehicle power mode master (PMM) is the instrument panel cluster (IPC). The ignition switch is a low current switch with multiple discrete circuits to the IPC. The IPC logic uses the ignition switch positions to identify the operator's desired power mode and activate specific discrete signals, and serial data messages for the operation of different subsystems as necessary. Other modules which have switched voltage inputs may operate in a default mode if the PMM serial data message does not match what the individual module can detect from its own connections.
The PMM will activate relays and other direct outputs of the PMM as needed according to the calculated power mode. Some relays controlled by the IPC are switched ignition voltage outputs that are pass through circuits within the BCM directly from the ignition switch. If these circuits short to ground, the B+ circuit fuse to the ignition switch will open.
Conditions for Running the DTC
The ignition switch is in the ACCESSORY, RUN, or CRANK positions.
Conditions for Setting the DTC
* Ignition circuit is shorted to voltage.
* Ignition circuit is open.
* Ignition, accessory, or off/run/crank circuit shorted to ground.
* B+ circuit of the ignition switch is open or shorted to ground.
* Ignition relay control circuit open, including relay coil and ground.
* Accessory circuit is shorted to voltage.
* Accessory circuit is open.
* IPC detects an open or short to voltage on the off/run/crank signal circuit when both ignition ACCESSORY/RUN and ignition RUN/CRANK parameters are active.
Actions Taken When the DTC Sets
* The IPC operates in a fail-safe power mode dependent on the last valid power mode detected and the state of the engine run flag data on the serial data communications circuits.
* The other modules on the vehicle operate in a fail-safe power mode dependent on the last valid power mode transmitted by the IPC and the state of the engine run flag on the serial data communications circuits.
Conditions for Clearing the DTC
* The condition responsible for setting the DTC no longer exists.
* A history DTC will clear once 50 consecutive malfunction-free ignition cycles have occurred.
Reference Information
Schematic Reference
* Power Distribution Schematics (without WHB) (Power Distribution Schematics (without WHB))Power Distribution Schematics (with WHB) (Power Distribution Schematics (with WHB))
* Power Moding Schematics (Power Moding Schematics)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Power Mode Description and Operation (Description and Operation)
Electrical Information Reference
* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Verification
With a scan tool, access IPC, Power Mode data display list and compare all parameters listed with the corresponding ignition key position. The IPC Power Mode Parameters table below illustrates the correct state of these input parameters in correspondence to the ignition switch position. The circuits which the individual parameters are related to are in parentheses.
If any parameters are incorrect in any key position, proceed to the Circuit/System Testing or Component Testing.
Circuit/System Testing
1. Disconnect the harness connector at the ignition switch.
2. Verify that a test lamp illuminates between B+ circuit terminal 2 and ground.
• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the circuits listed below for a short to ground.
Note: To help isolate a short to ground, it may be necessary to disconnect modules that are connected to the following circuits:
* Ignition terminal 3
* Ignition terminal 4
* Ignition terminal 1
* Ignition terminal 5
3. Connect the harness connector at the ignition switch.
4. Ignition OFF, key out, disconnect the A harness connector at the IPC. Verify that a test lamp does not illuminate between the ignition circuit terminals listed below and ground:
* terminal 2
* terminal 17
* terminal 18
• If the test lamp illuminates, test the ignition circuits for a short to voltage. If the circuit tests normal, replace the ignition switch.
5. Ignition in the ACCESSORY position, verify that a test lamp illuminates between the terminal 17 and ground.
• If the test lamp does not illuminate, test the ignition circuit for an open/high resistance. If the circuit tests normal, replace the ignition switch.
6. Ignition in the CRANK position, verify that a test lamp illuminates between terminal 18 and ground.
• If the test lamp does not illuminate, test the ignition circuit for an open/high resistance. If the circuit tests normal, replace the ignition switch.
7. If all of the circuits test normal, replace the IPC.
Component Testing
Ignition Switch
1. Ignition OFF, disconnect the harness connector at the ignition switch.
2. Verify the resistance between the terminals listed below match for each ignition switch position.
• If not the specified value, replace the ignition switch.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the repair.
* Ignition and Start Switch Replacement (Service and Repair)
* Control Module References (Programming and Relearning) for IPC replacement, setup, and programming