GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2006 🢒 Epica 🢒 Restraints 🢒 SIR 🢒 DTC B1487

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. If the resistance is between 2-10 kilo ohms, the defect may occur depending upon the SDM. The normal resistance is over 10 kilo ohms.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B1487 Passenger Frontal Deployment Loop Stage 2 Short to Ground

Conditions for Running the DTC

Ignition voltage is within the normal operating voltage range.

Conditions for Setting the DTC
    • The air bag wiring of the 2nd stage passenger high is shorted to ground.
    • The air bag wiring of the 2nd stage passenger low is shorted to ground.

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

Schematic Reference: SIR Schematics

Connector End View Reference: SIR Connector End Views

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.

1

Did you perform a Diagnostic System Check - Vehicle?

 

Go to Step 2

Go to Diagnostic System Check - Vehicle

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

Has the SDM discharged?

--

Go to Step 3

--

3

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

Is the air bag wiring damaged?

--

Go to Step 6

Go to Step 4

4
  1. Confirm the ignition switch is OFF.
  2. Remove the instrument panel (I/P) module.
  3. Disconnect the connector of the SDM wiring.
  4. Measure the resistance between the high, low wiring of the 2nd stage I/P module connector and ground.

Is the resistance equal to the specified value?

10K ohms

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

--

7

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

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