Service Information

Cruze

DTC B1370

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: Control Module Ignition On and Start Circuit Short to Battery

DTC B1370 06: Control Module Ignition On and Start Circuit Open

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Instrument Cluster Ignition Terminal 32	B1370 06	B1370 06	B1370 01	--
Ignition Run/Crank Relay Ignition Terminal 85	B1370 06	B1370 06	--	--
Ignition Run/Crank Relay Ground Terminal 86	--	B1370 06	--	--
Ignition Run/Crank Relay B+ Terminal 30	--	B1370 06	--	--

Circuit/System Description

The vehicle power mode master is the body control module (BCM). The ignition switch is a low current switch with multiple discrete circuits to the BCM.

The power mode master will activate relays and other direct outputs of the power mode master 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

B1370 01

Ignition switch is in the Accessory position.

B1370 06

Ignition switch is in the Accessory, Run, or Crank positions.

Conditions for Setting the DTC

B1370 01

Ignition circuit is shorted to voltage.

B1370 06

•	Ignition circuit is open.

•	Ignition or run/crank relay circuit is shorted to ground.

•	B+ circuit of the ignition run/crank relay is open or shorted to ground.

•	Ignition run/crank relay control circuit open, including relay coil and ground.

Action Taken When the DTC Sets

The Instrument Cluster still functions except check engine light is always off.

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

•	Instrument Cluster Schematics

•	Power Distribution Schematics

•	Power Moding Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

•	Instrument Cluster Description and Operation

•	Power Mode Description and Operation

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Verify that DTC B144B is not set.

⇒	If the DTC is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .

Circuit/System Testing

Ignition OFF, disconnect the KR73 ignition run/crank relay.
Test for less than 10 Ω between the ground circuit terminal 86 and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

Ignition ON, verify that a test lamp illuminates between the Ignition circuit terminal 85 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 K9 BCM.

Ignition OFF, reconnect the KR73 ignition run/crank relay.
Disconnect the harness connector at the P16 Instrument Cluster.
Ignition ON, verify that a test lamp illuminates between the ignition terminal 32 and ground.

⇒

If the test lamp does not illuminate and the Ignition fuse is good, test the ignition circuit for an open/high resistance. If the circuit tests normal, replace the KR73 ignition run/crank relay. If the ignition fuse is open, test the ignition circuit for a short to ground. If the circuit tests normal, replace the P16 instrument cluster.

If all circuits test normal, replace the P16 instrument cluster.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

•	Instrument Cluster Replacement

•	Relay Replacement

•	Control Module References for BCM replacement, programming and setup