Wiring System and Power Management
DTC B1370
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* 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 Battery
DTC B1370 04
- Device Ignition 1 Circuit Open Circuit
Conditions for Running the DTC
B1370 01
Ignition switch is in the OFF or ACC positions.
B1370 04
Ignition switch is in the START position.
Conditions for Setting the DTC
B1370 01
Ignition 1 voltage circuit is shorted to voltage for more than 2 seconds.
B1370 04
* Ignition 1 voltage circuit is open for more than 2 seconds.
* Ignition 1 voltage, accessory voltage, or off/run/crank voltage circuit shorted to ground.
* Battery positive voltage circuit of the ignition switch open or shorted to ground.
* Run crank relay coil control circuit open (including relay coil and ground).
Conditions for Clearing the DTC
* A current DTC clears when the malfunction is no longer present.
* A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.
Circuit/System Verification
1. Verify that the following DTCs are not set: U1814, B1428.
• If either of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle. Diagnostic Trouble Code Descriptions
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.
If any parameters are incorrect in any key position, proceed to the Circuit/System Testing or Component Testing below.
Circuit/System Testing
Important: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
1. Inspect the Ign Switch fuse for open. The fuse should be OK.
• If the fuse is open, test the following circuits for a short to ground, if all circuits test OK, replace the BCM.
* Battery positive voltage of the ignition switch
* Accessory voltage
* Off/Run crank voltage
* Ignition 1 voltage
2. Disconnect the ignition switch connector.
3. Test for battery positive voltage between the battery positive voltage circuit of the ignition switch and ground.
• If less than battery positive voltage, repair the circuit for an open/high resistance
Important: 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.
• If the ignition switch fails, replace the ignition switch.
5. Ignition OFF, disconnect BCM connector C1, test for less than 1.0 voltbetween the following circuits of the BCM and ground.
6. Ignition key out, test for less than 1.0 volt between the following circuits of the BCM and ground.
* Ignition key resistor signal
* Off/Run crank
* Accessory voltage
* Ignition 1 voltage
• If more than 1.0 volt, repair the circuit for a short to voltage.
7. Test for less than 1.0 ohm of resistance between the BCM and the ignition switch on the following circuits.
* Ignition key resistor signal
* Off/Run crank
* Accessory voltage
* Ignition 1 voltage
• If greater than 5 ohms, repair the circuit for open/high resistance
8. Test for infinite resistance between the ignition key resistor signal circuit of the BCM and ground.
• If less than infinite resistance, repair the signal circuit for a short to ground.
9. Replace the BCM.
Component Testing
Ignition Switch
Using the Resistance Test below, check the resistance between the pins of the ignition switch listed in each switch position listed.
If any reading is other than specified, replace the ignition switch.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
* Control Module References for BCM replacement, setup, and programming Programming and Relearning
* Ignition and Start Switch Replacement Verification Tests