GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2008 🢒 Optra 🢒 Safety and Security 🢒 Supplemental Inflatable Restraints 🢒 DTC B1485

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 B1485 Passenger Frontal Deployment Loop Stage 2 Resistance Above 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 over 3 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 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?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

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

Is the connector disconnected?

--

Go to Step 3

Go to Step 4

3

Reconnect the connector.

Is the action complete?

--

Go to Step 8

--

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

Is the resistance equal to the specified value?

0 ohms

Go to Step 5

Go to Step 7

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 6

6

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

Is the replacement complete?

--

Go to Step 8

--

7

Replace the air bag wiring.

Is the replacement complete?

--

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