GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2008 🢒 Optra 🢒 DTC 🢒 DTC B1486

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.

These test ignition and deployment loop voltages are measured to ensure that they are within their 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 deployment loops.

The SDM inspects the wiring connection to the I/P 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 B1486 Passenger Frontal Deployment Loop Stage 2 Resistance Below Threshold

Conditions for Running the DTC

Ignition voltage is within the normal operating voltage range.

Conditions for Setting the DTC
    • The resistance of the passenger air bag deployment loop is lower than 1.4 ohms.
    • The shorting bar is damaged and the SDM must be replaced.

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 Handling Caution in the Preface section.

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

Schematic Reference: SIR Schematics

Connector End View Reference: Component Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

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Go to Step 2

Go to Diagnostic System Check - Vehicle

2
  1. Confirm the ignition switch is OFF and the sensing and diagnostic module (SDM) fuse has been removed.
  2. Wait for 1 minute to discharge the SDM charger.

Has the SDM discharged?

--

Go to Step 3

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3

Visually inspect the connector and the wiring of the passenger air bag.

Is the wiring damaged?

--

Go to Step 6

Go to Step 4

4
  1. Confirm the ignition switch is OFF.
  2. Disconnect the connector of the instrument panel (I/P) module.
  3. Disconnect the connector of the SDM.
  4. Measure the resistance between terminal 43 and 44 of the SDM connector.

Is the resistance equal to the specified value?

∞

Go to Step 5

Go to Step 6

5
  1. Replace the SDM. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  2. Confirm the ignition switch is ON.
  3. Use the scan tool in order to clear the DTCs.
  4. Perform the Diagnostic System Check - Vehicle .

Is the DTC removed?

--

Go to Step 8

Go to Step 7

6

Replace the air bag wiring.

Is the replacement complete?

--

Go to Step 8

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7

Replace the I/P module. Refer to Inflatable Restraint Instrument Panel Module Replacement .

Is the replacement complete?

--

Go to Step 8

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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