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 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 | 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. 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 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.

### 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

### 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.

• | SDM

• | SDM wiring harness

1. Ignition OFF, remove the under hood SIR Display Fuse 25.
2. Ignition ON, test for 9-16 volts between the voltage supply side and ground.

⇒ | If not the specified range, refer to DTC B1370.

3. Ignition OFF, remove the SDM harness connector.
4. Ignition OFF, test for less then 1 ohm between the ignition 1 voltage circuit terminal 32 and the under hood fuse block terminal 28.

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

5. Ignition ON, with a DMM, test for less then 1 volt between the ignition 1 voltage circuit terminal 32 and the under hood fuse block terminal 28.

⇒ | If greater then the specified value, test the circuit for a short to voltage.

6. 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 SDM replacement, setup, and programming