Computer/Integrating System Diagnosis

DTC B1370

DTC DESCRIPTOR

DTC B1370 01
Device Ignition 1 ON and START Circuit Short to Battery

DTC B1370 06
Device Ignition 1 ON and START Circuit Open

DIAGNOSTIC FAULT INFORMATION




Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Testing and Inspection

Refer to Power Mode Description and Operation for other power mode parameters.

Ignition Run/Crank:

TYPICAL SCAN TOOL DATA

CIRCUIT/SYSTEM DESCRIPTION
As the power mode master (PMM), the body control module (BCM) monitors the ignition inputs off/run/crank voltage, ignition 1 voltage and the accessory voltage signals supplied from the ignition switch. The BCM uses the sequence that the signals appear, their voltage levels, the engine run flag (ERF) status and the remote start status to determine the power mode.

When the ignition switch is placed in the RUN or CRANK position, the switch supplies B+ to the BCM ignition 1 voltage input terminal. If this circuit becomes shorted to B+, ground or the circuit opens, DTC B1370 will set.

CONDITIONS FOR RUNNING THE DTC

B1370 01
Ignition switch is in the OFF or ACC positions.

B1370 06
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 06
Ignition 1 voltage circuit is open for more than 2 seconds.

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.

DIAGNOSTIC AIDS
Use the DMM MIN/MAX function to capture/locate intermittent conditions.

CIRCUIT/SYSTEM VERIFICATION

IMPORTANT: The engine may crank during this procedure.

Using a scan tool monitor the Ignition Run/Crank parameter while turning the ignition switch. Compare the parameter state with the typical scan tool data above.
- If the Ignition Run/Crank parameter is in normal range for all ignition switch positions and the DTC is current, replace the BCM.

CIRCUIT/SYSTEM TESTING
1. With the ignition OFF, disconnect the BCM.
2. With the ignition in OFF and ACC, measure for less than 0 volts between the ignition 1 voltage circuit of the BCM connector and ground.
- If over 0 volts, disconnect the ignition switch and check the ignition 1 voltage circuit for short to voltage or short to other ignition switch signal circuit. If the circuit tests normal, test or replace the ignition switch.
3. With the ignition in RUN and START, measure for battery voltage between the ignition 1 voltage circuit at the BCM connector and ground.
- If less than battery voltage, disconnect the ignition switch and check the ignition 1 voltage and battery positive voltage circuits for an open or short to ground. If the circuits test normal, test or replace the ignition switch.
4. If all circuits test normal, replace the BCM.

COMPONENT TESTING
1. While turning the ignition switch in all positions, measure for continuity between battery voltage and ignition 1 run/crank terminals at the ignition switch.
- If continuity in the OFF and ACC positions, or no continuity in the RUN and START positions, replace the ignition switch.

REPAIR INSTRUCTIONS
Perform the Diagnostic Repair Verification after completing the repair. Verification Tests

- Control Module References for BCM replacement, setup, and programming.
- Ignition Switch Replacement.