GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2005 🢒 STS 🢒 DTC 🢒 DTC B1370

Circuit Description

The inflatable restraint sensing and diagnostic module (SDM) monitors the Ignition 1 from the ignition switch. When the vehicle ignition is placed in the RUN or CRANK position the switch supplies Ignition 1 voltage to the SDM. If an open, short to voltage, or short to ground in this SDM ignition 1 circuit is detected then DTC B1370 will set.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B1370 Device Ignition 1 (ON and Start) Circuit

This vehicle has DTCs which include DTC symptoms. For more information on DTC symptoms refer to DTC Symptom Description in Vehicle DTC Information.

Symptom

Symptom Descriptor

01

Short to Battery

06

Short to Ground or Open

Conditions for Running the DTC

Ignition 1 voltage is within the normal operating range of 9-16 volts.

Conditions for Setting the DTC

B1370 01

    • The SDM detects a short to battery in the ignition 1 voltage circuit when the switch is in the OFF position.
    • This condition is present at least 10 seconds.

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.
    • This condition is present at least 10 seconds.

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. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This checks the voltage from the supply voltage side of the AIR BAG fuse.

    2.

  2. This test the ignition 1 voltage circuit between the output side of the AIR BAG fuse and the SDM connector for high or low resistance or an open

    3.

  3. This test the ignition 1 voltage circuit in the SDM harness connector for a short to voltage or ground.

Step

Action

Values

Yes

No

Schematic Reference: SIR Schematics

Connector End View Reference: SIR Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

    Important: J-45289 CANdi module must be used with the scan tool.

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.

Does the scan tool display DTC B1370 as current?

--

Go to Step 3

Go to Diagnostic Aids

3

  1. Remove the AIR BAG fuse in the right rear fuse block.
  2. Measure the voltage from the supply voltage side of the AIR BAG ignition 1 fuse to a ground.

Does the voltage measure within the specified value?

9-16 V

Go to Step 4

Go to Charging System Test in Engine Electrical

4

  1. Turn OFF the ignition.
  2. Disconnect the inflatable restraint sensing and diagnostic (SDM) connectors. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.
  3. Inspect the SDM for corrosion or poor connections that may cause a malfunction in the ignition 1 voltage circuit. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 8

Go to Step 5

5

  1. Turn OFF the ignition.
  2. Test the ignition 1 voltage circuit between the output side of the AIR BAG fuse and the SDM harness connector for high or low resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 8

Go to Step 6

6

  1. Turn ON the ignition, with the engine OFF.
  2. Test the ignition 1 voltage circuit in the SDM harness connector for a short to voltage or ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 8

Go to Step 7

7

  1. Turn OFF the ignition.
  2. Replace the SDM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 8

--

8
  1. Connect the AIR BAG fuse and all SIR components.
  2. Turn ON the ignition, with the engine OFF.
  3. Use the scan tool in order to clear the DTCs.
  4. Operate the vehicle within the Conditions for Running the DTCs as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK