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 1 Circuit | B1370 06 | -- | B1370 06 | B1370 01 | B1370 06

### 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 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

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

### Reference Information

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

### 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.

• | The SDM module

• | The SDM wiring harness connector

1. Ignition ON, use the scan tool checks for DTCs. Verify that DTC P2535 in the BCM does not set.

⇒ | If DTC P2535 is current go to DTC P2535 .

2. Ignition OFF, remove the Air Bag fuse from the BCM fuse center. Ignition ON, engine OFF test the voltage side of the Air Bag fuse with a DMM. Measure the voltage of the Air Bag fuse voltage side and ground. The voltage should read 9-16 volts.

⇒ | If the voltage is less than 9-16 volts refer to DTC B1370 .

3. Remove the SDM connector.
4. With the Air Bag fuse removed, test the ignition 1 voltage circuit between the BCM 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.

5. If all circuits test normal then 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