Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptors
DTC B1370 01: Device Ignition 1 Circuit Short To BatteryDTC B1370 04: Device Ignition 1 Circuit Open
DTC B1380 01: Device Ignition ACCESSORY Circuit Short to Battery
DTC B1380 04: Device Ignition ACCESSORY Circuit Open
DTC B1441 02: Device Ignition OFF, RUN, and CRANK Circuit Short to Ground
DTC B1441 06: Device Ignition OFF, RUN, and CRANK Circuit Short to Ground or Open
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage |
|---|---|---|---|
B+ - Terminal 2 | B1370 04, B1380 04 | B1370 01, B1380 01, | B1370 01, B1380 01, |
Ignition Terminal 4 | B1380 04 | B1380 01 | B1380 01 |
Ignition Terminal 3 | B1370 04 | B1370 01 | B1370 01 |
Ignition Terminal 5 | B1441 02, B1441 06 | B1441 06 | -- |
Circuit/System Description
The vehicle power mode master (PMM) is the body control module (BCM). The ignition switch is a low current switch with multiple discrete ignition switch signals to the PMM for determination of the power mode. The PMM receives the ignition switch signals, and additionally a reference voltage signal from the BCM, through the ignition switch, and back to the BCM. There are redundancies within the PMM system that can allow operation of certain subsystems when there are faults in the ignition switch circuits. Other information such as serial data input from other modules and DTCs is also used to determine what power mode signals and information is transmitted by the PMM. The BCM logic uses all this information 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 BCM 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
Voltage supplied to the module is in the normal operating voltage range of 9-16 volts.
Conditions for Setting the DTC
B1370 01, B1370 04
| • | The BCM detects a short to ground in the ignition 1 voltage circuit when the ignition switch is in RUN or CRANK. |
| • | The BCM detects a short to battery or an open in the ignition 1 voltage circuit when the switch is in the OFF position. |
B1380 01, B1380 04
| • | The BCM detects a short to ground in the ACCESSORY voltage circuit when the ignition switch is in RUN or CRANK. |
| • | The BCM detects a short to battery or an open in the ACCESSORY voltage circuit when the switch is in the OFF position. |
B1441 02, B1441 06
| • | The BCM detects a short to ground in the OFF/RUN/CRANK voltage circuit when the ignition switch is in RUN or CRANK. |
| • | The BCM detects a short to battery or an open in the OFF/RUN/CRANK circuit. |
Actions Taken When the DTC Sets
| • | The BCM stores DTC to memory. |
| • | The BCM 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 BCM and the state of the engine run flag on the serial data communications circuits. |
Conditions for Clearing the DTC
A current DTC clears when the malfunction is no longer present.
Diagnostic Aids
The power modes and controls are determined using BCM logic. Comparing the Body Control Module Power Mode data display parameters listed in Circuit/System Verification to the scan tool values of the vehicle will determine if there is a power mode fault.
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Power Mode Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
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 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, refer to the Circuit/System Testing or Component Testing. |
Ignition Switch Position | Power Mode | Run Relay Command (Terminal 5) | Ignition Switch Accessory Signal (Terminal 4) | Run/Crank Relay Command (Terminal 3) |
|---|---|---|---|---|
Operating Conditions: Driver door open to disable RAP | ||||
Off Key Out | Off | Off | Inactive | Off |
Off Key IN | Off | Off | Inactive | Off |
Accessory | Accessory | Off | Active | Off |
Run | Run | On | Active | On |
Start | Crank Request | Off | Inactive | On |
Circuit/System Testing
- Connect a test lamp between each fuse test terminal of the ignition switch B+ circuit fuse and ground. The test lamp should illuminate.
- Disconnect the harness connector at the ignition switch.
- Connect a test lamp between the B+ circuit terminal 2 and ground. The test lamp should illuminate.
- Perform the ignition switch component test. Verify the switch passes the test.
- Disconnect X2 and X4 harness connectors at the BCM, test for less than 1.0 volt between the circuit terminals of the BCM listed below and ground:
- Test for less than 1.0 ohm between the BCM and the ignition switch on the circuits listed below:
- If all circuits test normal, replace the BCM.
Note: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
| ⇒ | If the test lamp does not illuminate, test the ignition switch circuits listed below for a short to ground. If all circuits test OK, replace the BCM. |
| • | B+ terminal 2 |
| • | Ignition terminal 4 |
| • | Ignition terminal 3 |
| • | Ignition terminal 5 |
| ⇒ | If the test lamp does not illuminate, test the B+ circuit for an open/high resistance. |
Note: The ignition switch component test must be performed before proceeding with this test to verify the integrity of the switch.
| ⇒ | If the ignition switch does not test normal, replace the ignition switch. |
| • | Ignition terminal C8, X4 |
| • | Ignition terminal D3, X4 |
| • | Ignition terminal 56, X2 |
| ⇒ | If greater than specified, test the circuit for a short to voltage. |
| • | Ignition terminal C8, X4 and 4 |
| • | Ignition terminal D3, X4 and 3 |
| • | Ignition terminal 56, X2 and 5 |
| ⇒ | If greater than specified, test the circuit for open/high resistance. |
Component Testing
Ignition Switch
- Ignition OFF, disconnect the harness connector at the ignition switch.
- Verify the resistance between the terminals listed below match for each ignition switch position.
| ⇒ | If not the specified value, replace the ignition switch. |
Ignition Switch Position | Terminals 2 and 3 | Terminals 2 and 5 | Terminals 2 and 6 | Terminals 5 and 6 |
|---|---|---|---|---|
Off Key Out | Infinite | Infinite | Infinite | Infinite |
Off Key IN | Infinite | < 5.0 ohms | Infinite | Infinite |
Accessory | Infinite | Infinite | Infinite | Infinite |
Run | < 5.0 ohms | Infinite | Infinite | < 5.0 ohms |
Start | < 5.0 ohms | Infinite | Infinite | 1275-1325 ohms |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for BCM replacement, setup, and programming |
