For 1990-2009 cars

### Circuit Description

Inflatable Restraint Sensing and Diagnostic module (SDM) monitors ignition 1 voltage of the ignition switch. When the ignition switch is at RUN or CRANK, the switch provides SDM with ignition 1 voltage. If the SDM detects ignition 1 circuit open, short to voltage or ground, DTC B1370 will set.

### DTC Descriptor

The diagnostic procedure supports the following DTC:

DTC B1370 Ignition 1 (ON and START) Circuit

The vehicle has DTCs including the DTC symptoms. Refer to DTC Symptom Description for more DTC information.

DTC Symptom | DTC Symptom Descriptor
--- | ---
01 | Short to battery
06 | Short to ground or open

### Conditions for Running the DTC

Ignition 1 voltage is within 9-16 volts.

### Conditions for Setting the DTC

#### B1370 01

• | When ignition is OFF, the SDM detects ignition 1 voltage is short to battery.

• | It lasts for 10 seconds.

#### B1370 06

• | When ignition is at RUN or CRANK, the SDM detects ignition 1 voltage is short to ground circuit or open circuit.

• | It lasts for 10 seconds.

### Action Taken When the DTC Sets

• | The SDM commands the AIR BAG indicator ON via GMLAN serial data communications.

• | The SDM stores the DTC into the memory.

• | The SDM determines the power mode according to GMLAN power mode information. During other time of the ignition cycle, it ignores the ignition 1 input.

### Conditions to Clearing the DTC

• | The current DTC will be cleared away after the trouble is removed.

• | When the ignition cycle counter has reached the newly set threshold and no trouble occurs repeatedly, the history DTC will be cleared.

### Diagnostic Aids

History DTC may result from intermittent short or open circuit of ignition 1 circuit. Refer to Testing for Intermittent Conditions and Poor Connections .

### Test Description

The following numbers are corresponding to the steps in the diagnostic table.

1. This step tests the voltage of the airbag fuse.

2. This step tests if the ignition 1 voltage circuit between the airbag fuse output and SDM harness connector has high or low resistance or is open.

3. This step tests if the ignition 1 voltage circuit between SDM harness connector is short to voltage or ground.

Step | Action | Value | Yes | No
--- | --- | --- | --- | ---
Schematic Reference: SIR Schematics Connector End View Reference: SIR Connector End Views
1 | Have you conducted Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 | Important: J-45289 CANdi Module must be used together with the scan tool.

1. Install the scan tool.
2. Engine off, ignition on.

Does the scan tool indicate DTC B1370 as current trouble code?

--

Go to Step 3

Go to Diagnostic Aids

3 |

1. Remove the airbag fuse from the right rear fusebox.
2. Measure the voltage between the airbag fuse signal and ground.

Is the measured voltage within the specified value?

9-16V

Go to Step 4

Go to Air Bag Indicator Circuit Malfunction

4 |

1. Turn the ignition switch to OFF position.
2. Disconnect the SIR system sensing and diagnostic module (SDM) connector. Refer to Control Module References for replacement, set up, and programming.
3. Check if the SDM has corrosion or poor connections that may result in ignition 1 voltage circuit fault. Refer to Testing for Intermittent Conditions and Poor Connections .

Do you find and correct the condition?

--

Go to Step 8

Go to Step 5

5 |

1. Turn the ignition switch to OFF position.
2. Test if the ignition 1 voltage circuit between the airbag fuse output and SDM harness connector has high or low resistance or is open. Refer to Circuit Testing and Wiring Repairs .

Do you find and correct the condition?

--

Go to Step 8

Go to Step 6

6 |

1. Engine off, ignition on.
2. Test if the battery positive voltage circuit between the airbag fuse output and SDM harness connector is short to voltage or ground. Refer to Circuit Testing and Wiring Repairs .

Do you find and correct the condition?

--

Go to Step 8

Go to Step 7

7 |

1. Turn the ignition switch to OFF position.
2. Replace the SDM module. Refer to Control Module References for replacement, set up, and programming.

Have you finished the replacement?

--

Go to Step 8

--.

8 |

1. Connect the airbag fuses and all SIR components.
2. Engine off, ignition on.
3. Clear away all DTCs with scan tool.
4. Operate the vehicle under conditions when DTC runs as specified in supporting documents.

Does the DTC set again?

--

Go to Step 2

System OK