For 1990-2009 cars

### 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 and 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 | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance
--- | --- | --- | --- | --- | ---
Ignition | B1370 06 | B1370 06 | B1370 06 | B1370 01 | --

### Circuit/System Description

The inflatable restraint sensing and diagnostic module (SDM) monitors the ignition 1 signal from the ignition switch. When the vehicle ignition switch is placed in the RUN or CRANK position the switch supplies voltage to the SDM ignition 1 input terminal. If an open, short to voltage, or short to ground in this SDM ignition 1 circuit is detected 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.

### Action Taken When the DTC Sets

• | The SDM requests the instrument panel cluster (IPC) to illuminate the AIR BAG indicator.

• | 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

A history DTC maybe caused by an intermittent short or open in the ignition 1 circuit.

### Reference Information

#### Schematic Reference

SIR Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

SIR System 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 Testing

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

• | SDM module

• | SDM wiring harness connector

1. Ignition ON, verify DTC B1370 is not set in any other modules.

⇒ | If the DTC is set in other modules, refer to DTC B1370-B1379, B1380-B1389, or B1440-B1443 and diagnose other modules prior to diagnosing the SDM.

2. Ignition OFF, disconnect the harness connector at the SDM.
3. Verify a test lamp does not illuminate between the ignition circuit 33 and ground.

⇒ | If the test lamp illuminates, test the ignition circuit for a short to voltage. If the circuit tests normal, replace the BCM.

4. Ignition ON, verify a test lamp illuminates between the ignition circuit terminal 33 and ground.

⇒ | If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.

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

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | SIR/SRS Wiring Repairs

• | Control Module References for BCM and SDM replacement, setup, and programming