B1390

DTC B1390

DTC DESCRIPTOR

DTC B1390
Device Voltage Reference Input Circuit

DIAGNOSTIC FAULT INFORMATION
Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview

CIRCUIT/SYSTEM DESCRIPTION
The body control module (BCM) supplies a 12-volt reference to the ignition switch. Based on the position of the ignition switch, the 12-volt reference provides feedback to the BCM to determine ignition switch position.

CONDITIONS FOR RUNNING THE DTC
The BCM is awake.

CONDITIONS FOR SETTING THE DTC
10 consecutive ignition cycles in which the 12-volt reference does not equal the ignition 1, ignition 3, or crank voltage input.

ACTION TAKEN WHEN THE DTC SETS
Loss of communication and low/high voltage DTCs are suspended.

CONDITIONS FOR CLEARING THE DTC
- A current DTC clears when the malfunction is no longer present.
- A history DTC will clear after 100 malfunction-free ignition cycles.

CIRCUIT/SYSTEM TESTING
1. Ignition OFF, disconnect the harness connector at the ignition switch.
2. Test for 11.8-12.2 volts between the 12-volt reference circuit terminal 6 and ground.
- If less than the specified range, test the 12-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
- If greater than the specified range, test the 12-volt reference circuit for a short to voltage. If the circuit tests normal, replace the BCM.
3. Test for 11.8-12.2 volts between the 12-volt reference circuit terminal 4 and ground.
- If less than the specified range, test the 12-volt reference circuit for a short to ground or an open/high resistance.
- If greater than the specified range, test the 12-volt reference circuit for a short to voltage.
4. Connect the harness connector at the ignition switch.
5. Disconnect the harness connector C1 at the BCM.
6. Install a jumper wire between the 12-volt reference circuit terminal 25 and the 12-volt reference circuit terminal in the BCM.
7. With the ignition in the OFF position, test for 0 volts at the following circuit terminals:
- Ignition 1 circuit terminal 22
- Ignition 3 circuit terminal 23
- Crank voltage circuit terminal 21
- If greater than 0 volts, test the applicable circuit for a short to voltage. If all circuits test normal, test or replace the ignition switch.
8. With the ignition in the ACCY position, test for 11.8-12.2 volts at the ignition 3 circuit terminal 23.
- If less than the specified range, test the ignition 3 circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the ignition switch.
- If greater than the specified range, test the ignition 3 circuit for a short to voltage. If the circuit tests normal, replace the ignition switch.
9. With the ignition in the RUN position, test for 11.8-12.2 volts at the follow circuit terminals:
- Ignition 1 circuit terminal 22
- Ignition 3 circuit terminal 23
- If less than the specified range, test the applicable circuit for a short to ground or an open/high resistance. If the circuits test normal, test or replace the ignition switch.
- If greater than the specified range, test the applicable circuit for a short to voltage. If the circuit tests normal, replace the ignition switch.
10. With the ignition in the CRANK position, test for 11.8-12.2 volts at the crank voltage circuit terminal 21.
- If less than the specified range, test the crank voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the ignition switch.
- If greater than the specified range, test the crank voltage circuit for a short to voltage. If the circuit tests normal, test or replace the ignition switch.
11. If all circuits test normal, test or replace the BCM.

REPAIR INSTRUCTIONS
Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests
- Ignition and Start Switch Replacement
- Control Module References for BCM replacement, setup and programming. Programming and Relearning