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 BatteryDTC 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 Voltage | B1370 06 | -- | B1370 06 | B1370 01 | B1370 06 |
Run/Crank Relay Coil Control | 1 | -- | 1 | 1 | 1 |
1. A fault in this circuit will cause multiple symptoms including no start and may cause B1370 in the SDM. | |||||
Circuit/System Description
The inflatable restraint sensing and diagnostic module (SDM) monitors the ignition 1 voltage circuit from the Run/Crank relay. The SDM also compares the ignition 1 voltage 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 voltage circuit. If a fault is detected in the SDM ignition 1 voltage 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 voltage input. |
| • | An open circuit on the in the run/crank relay coil control circuit 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
DTC B1370 06 will set if there is an inoperative Run/Crank relay or current fault on the control circuit of the relay, however there will be multiple concerns with other modules including the engine control and transmission control modules. The vehicle may not start and the SIS MIL lamp may be inoperative with the ignition key ON.
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the SDM. Refer to SDM replacement.
- Connect a test lamp between the ignition 1 voltage circuit terminal 32 and ground.
- Cycle the ignition switch between the RUN and OFF positions. The test lamp should turn ON and OFF as the switch is cycled.
- Test or replace the SDM.
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
| ⇒ | If the test lamp is always ON, test the ignition 1 voltage circuit of the SDM and the control circuit of the Run/Crank relay for a short to voltage. If the circuits test normal, replace the Run/Crank relay. |
| ⇒ | If the test lamp is always OFF, test the ignition 1 voltage circuit of the SDM and the control circuit of the Run/Crank relay for an open or short to ground. If the circuits test normal, replace the Run/Crank relay. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for SDM replacement, setup, and programming |
