B1370

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 06
- Device Ignition 1 Circuit Short to Ground or Open

Diagnostic Fault Information






Circuit/System Description

The inflatable restraint sensing and diagnostic module (SDM) monitors the ignition 1 signal from the ignition switch. The SDM also compares the ignition 1 input to the power mode message communicated over the vehicle bus. When the vehicle ignition switch is placed in the RUN or CRANK position, voltage is applied to the SDM ignition 1 input terminal. If a fault is detected in the SDM ignition 1 circuit, then DTC B1370 will set.

Conditions for Running the DTC

Ignition voltage is between 9-16 volts.

Conditions for Setting the DTC

The following conditions exist for at least 10 seconds.

B1370 01

The SDM detects a short to battery in the ignition 1 voltage circuit when the switch is in the OFF position.

B1370 06
* The SDM detects a short to ground or an open in the ignition 1 voltage circuit when the ignition switch is in RUN or CRANK.
* The SDM sees that the vehicle power mode message is Run/Crank but does not detect the Run/Crank voltage on the ignition 1 input.
* There is an open circuit on the in the control side of the RUN/Crank relay.

Action Taken When the DTC Sets

* The SDM commands the AIR BAG indicator ON via serial data communications.
* The SDM stores DTC to memory.
* The SDM determines its power mode only from the GMLAN power mode messages and discards the ignition 1 input for the remainder of the ignition cycle.

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

The SIR fuse could be open and DTC B1370 will set if the low reference circuit is shorted to voltage/battery with no sensor code set for one of the following sensors:

* Right or Left front end sensors
* Right or Left side impact sensors

There is a current fault on the control side of the RUN/CRANK relay.

Circuit/System Testing

1. Important: When removing connectors, inspect for damage or corrosion. Damage or corrosion in the following requires repair or replacement of the affected component/connector:

* The SDM module

* The SDM wiring harness connector

Ignition OFF, remove the Air Bag fuse from the underhood fuse center. Ignition ON, engine OFF test the voltage from the supply voltage side of the AIR BAG fuse to a ground with a DMM. The voltage should read 9-16 volts.

• If the voltage is less than 9-16 volts, correct the open or short on the voltage supply circuit or the open in the control side of the RUN/CRANK relay.

2. Remove the SDM connector. With the air bag fuse removed, test the ignition 1 voltage circuit between the underhood fuse center and the SDM for a short to voltage or an open. Verify that a short to voltage or an open does not exist.

• If any of the above conditions are found, make the appropriate repair.

• If ignition 1 voltage circuit test normal then refer to Diagnostic Aids within this repair.

3. If all circuits test normal, replace the SDM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

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