GM Service Manual Online
For 1990-2009 cars only

Circuit Description

When the ignition switch is turned to ON, the sensing and diagnostic module (SDM) will perform a turn-on test to diagnose critical malfunctions within the SDM itself.

Upon passing this test, ignition and deployment loop voltages are measured to ensure they are within the normal voltage ranges. The SDM monitors the voltages at the driver low and the passenger low to detect shorts to ground or voltage in the deploy loops. The SDM inspects the wiring connection to the passenger side impact module by letting the infinitesimal current flow through the internal circuit and verify the resistance.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC 056 Right Side Air Bag Deployment Loop Resistance Too High

Conditions for Running the DTC

Ignition voltage is within the normal operating voltage range.

Conditions for Setting the DTC

The resistance of the right side impact module deployment loop is over 2.8 ohms.

Action Taken When the DTC Sets

The SDM commands the AIR BAG indicator ON.

Conditions for Clearing the DTC

The condition responsible for setting the DTC no longer exists and the scan tool Clear DTCs function is used.

Step

Action

Values

Yes

No

Caution: Refer to Sensing and Diagnostic Module Voltage after Ignition is Turned Off Caution in the Preface section.

Caution: Refer to Sensing and Diagnostic Module Handling Caution in the Preface section.

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

2

Visually inspect the right side impact module wiring and connector.

Is the air bag wiring damaged or the connector disconnected?

--

Go to Step 3

Go to Step 4

3

Repair the wiring or connect the connector.

Did you complete the repair?

--

Go to Step 8

--

4

  1. Confirm the ignition switch is OFF.
  2. Disconnect the connector of the right side impact module.
  3. Disconnect the connector of the sensing and diagnostic module (SDM).
  4. Measure the resistance between the terminal 1 and 2 of the right side impact module and the terminal 16 and 17 of the SDM.

Is the resistance equal to the specified value?

0 Ω

Go to Step 5

Go to Step 7

5

  1. Replace the SDM. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement.
  2. Connect the negative battery cable.
  3. Use the scan tool in order to clear the DTCs.
  4. Perform the Diagnostic System Check - Vehicle.

Is DTC 056 still shown as a current fault?

--

Go to Step 6

Go to Step 8

6

Replace the right side impact module.

Did you complete the replacement?

--

Go to Step 8

--

7

Replace the air bag wiring.

Did you complete the replacement?

--

Go to Step 8

--

8

  1. Reconnect all SIR components.
  2. Verify that all components, connectors and connector position assurances (CPAs) are properly mounted.
  3. Use the scan tool in order to clear the DTCs.
  4. Operate the vehicle within the Conditions for Running the DTC, as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK