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For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Cobalt 🢒 Restraints 🢒 SIR 🢒 DTC B1370

Circuit 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.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B1370 Device Ignition 1 Circuit

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 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 .

Test Description

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

  1. This tests the Air Bag ignition 1 voltage circuit for a short or open.

  2. This tests the Run/Crank voltage circuit between the relay and fuse.

    3.

  3. This tests the Run/Crank voltage circuit for an short or open.

Step

Action

Values

Yes

No

Schematic Reference: SIR Schematics and Power Distribution 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

2
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. Check if DTC P2535 is set in the body control module (BCM).

Does the scan tool display DTC P2535 in the BCM as current?

--

Go to DTC P2535

Go to Step 3

3

Measure the voltage from the voltage side of the AIR BAG (IGN) fuse in the BCM to ground.

Does the voltage measure within the specified value?

9-16 V

Go to Step 4

Go to Step 7

4

  1. Turn OFF the ignition.
  2. Disconnect the inflatable restraint sensing and diagnostic module (SDM) connector. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  3. Inspect for poor connections at the SDM connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

--

Go to Step 12

Go to Step 5

5
  1. Turn ON the ignition, with the engine OFF.
  2. Measure the ignition 1 voltage circuit in the SDM connector.

Does the voltage measure within the specified value?

9-16 V

Go to Step 11

Go to Step 6

6

Test the air bag ignition 1 voltage circuit between the BCM and the SDM for a short or open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 12

--

7

Measure the voltage from the voltage side of the RUN/CRANK fuse in the Underhood Junction Block to ground.

Does the voltage measure within the specified value?

9-16 V

Go to Step 8

Go to DTC P2535

8
  1. Disconnect the BCM harness connector containing the Run/Crank circuit. Refer to Body Control Module Replacement .
  2. Inspect module and connector for intermittent and poor connections. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

--

Go to Step 12

Go to Step 9

9

Test the Run/Crank voltage circuit between the BCM connector and the underhood junction block for a short or open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 12

Go to Step 10

10
  1. Turn OFF the ignition.
  2. Replace the BCM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 12

--

11
  1. Turn OFF the ignition.
  2. Replace the SDM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 12

--

12
  1. Connect all SIR and BCM 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