GM Service Manual Online
For 1990-2009 cars only

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. 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 GMLAN serial data.
    • 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

Schematic Reference

SIR Schematics

Connector End View Reference

SIR Connector End Views

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.
  2. If DTC P2535 is current go to DTC P2535 .
  3. 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.
  4. If the voltage is less than 9-16 volts refer to DTC B1370 .
  5. Remove the SDM connector.
  6. 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.
  7. If any of the above conditions are found make the appropriate repair.
  8. 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