GM Service Manual Online
For 1990-2009 cars only

Object Number: 260333  Size: SF
SIR Components
SIR Schematics
Handling ESD Sensitive Parts Notice
SIR Caution
Handling ESD Sensitive Parts Notice

Circuit Description

When you first turn the ignition switch to the RUN position, the inflatable restraint sensing and diagnostic module (SDM) performs tests to diagnose critical malfunctions within itself. Upon passing these tests IGNITION, 23VLR and the deployment loop voltages are measured to make sure they are within their respective normal voltage ranges. The SDM monitors the voltages at Driver Frontal Low terminal 2 and Passenger Frontal Low terminal 3 to detect shorts-to-B+ in the inflator module circuits.

Conditions for Setting the DTC

    • The voltage at Passenger Frontal Low terminal 3 is less than 3.8 volts.
    • The voltage at Driver Frontal Low terminal 2 is more than 3.8 volts for 500 milliseconds.

The CONTINUOUS MONITORING test checks for this DTC. This test occurs when IGNITION is within the normal operating voltage range.

Action Taken When the DTC Sets

    • The SDM sets a Diagnostic Trouble Code.
    • The SDM turns ON the AIR BAG warning lamp.

Conditions for Clearing the DTC

    • Current DTC-The voltage at Driver Frontal Low terminal 2 is less than 3.5 volts for 500 milliseconds.
    • History DTC
       - You issue a scan tool CLEAR CODES command.
       - Once 250 malfunction free ignition cycles have occurred.

Diagnostic Aids

A short-to-B+ in the inflatable restraint steering wheel module circuit can cause an intermittent condition. Inspect CKT 347 and CKT 348 carefully for cutting or chafing. The diagnostic table directs the technician to note the entry value of DRIVER FRONTAL SENSELO. Comparing the value of DRIVER FRONTAL SENSELO can be helpful in determining if an intermittent condition exists.

When measurements are requested in this table, use J 39200 Digital Multimeter with the correct terminal adapter from J 35616 Connector Test Adapter Kit. When a check for proper connection is requested, refer to Intermittents and Poor Connections . When a wire, connector or terminal repair is requested, use J-38125 Terminal Repair Kit and refer to Wiring Repair .

Test Description

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

  1. This test determines the driver frontal air bag low voltage measured by the inflatable restraint sensing and diagnostic module (SDM).

  2. This test isolates the malfunction to one side of the inflatable restraint steering wheel module coil yellow 2-way connector.

  3. This test determines whether the malfunction is due to the inflatable restraint steering wheel module or the module coil.

  4. This test determines whether the malfunction is in CKT 347.

  5. This test determines whether the malfunction is in CKT 348.

DTC B1025 Driver Deployment Loop Short to Voltage

Step

Action

Value(s)

Yes

No

1

Was the SIR Diagnostic System Check performed?

--

Go to Step 2

Go to SIR Diagnostic System Check

2

  1. Turn the ignition switch to the OFF position.
  2. Connect a scan tool to the DLC.
  3. Turn the ignition switch to the RUN position.
  4. Request the SIR data list display.
  5. Read and record on the repair order the driver frontal air bag low voltage DRIVER FRONTAL SENSELO.

Has the DRIVER FRONTAL SENSELO been read and recorded on the repair order?

--

Go to Step 3

--

3

  1. Turn the ignition switch to the OFF position.
  2. Disconnect the inflatable restraint steering wheel and IP module yellow 2-way connectors located near the base of the steering column and behind the RH insulator panel.
  3. Connect J 38715-A SIR Driver/Passenger Load Tool to the harness connectors.
  4. Turn the ignition switch to the RUN position.
  5. Using the scan tool, request the SIR data list display.
  6. Read the driver frontal air bag low voltage DRIVER FRONTAL SENSELO.

Is DRIVER FRONTAL SENSELO more than the specified value?

3.8 V

Go to Step 7

Go to Step 4

4

  1. Turn the ignition switch to the OFF position.
  2. Remove the inflatable restraint steering wheel module. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  3. Disconnect J 38715-A from the driver 2-way harness connector.
  4. Connect the driver 2-way connector at the base of the steering column.
  5. Connect J 38715-A to the upper inflatable restraint steering wheel module coil connector on the steering column.
  6. Turn the ignition switch to the RUN position.
  7. Using the scan tool, request the SIR data list display.
  8. Read the driver side low voltage DRIVER FRONTAL SENSELO.

Is DRIVER FRONTAL SENSELO more than the specified value?

3.8 V

Go to Step 6

Go to Step 5

5

  1. Turn the ignition switch to the OFF position.
  2. Replace the inflatable restraint steering wheel module. Refer to Inflatable Restraint Steering Wheel Module Replacement .

Are the repairs complete?

--

Go to Step 11

--

6

  1. Turn the ignition switch to the OFF position.
  2. Remove the inflatable restraint steering wheel module coil. Refer to Inflatable Restraint Steering Wheel Module Coil Replacement .
  3. Inspect the coil and the wires for damage.
  4. Replace the inflatable restraint steering wheel module coil. Refer to Inflatable Restraint Steering Wheel Module Coil Replacement .

Are the repairs complete?

--

Go to Step 11

--

7

  1. Turn the ignition switch to the OFF position.
  2. Disconnect the inflatable restraint Sensing and Diagnostic Module (SDM). Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  3. Disconnect the J 38715-A .
  4. Insert the J 42113 SIR shorting bar tool into the SDM harness connector above terminals 1 and 2.
  5. Turn the ignition switch to the RUN position.
  6. Measure the volatge on the SDM harness connector from terminal 1 to terminal 7 (ground).

Is the measured voltage less than the specified value?

1 V

Go to Step 9

Go to Step 8

8

Repair a short to voltage condition in CKT 347.

Are the repairs complete?

--

Go to Step 11

--

9

Measure the voltage on the SDM harness connector from terminal 2 to terminal 7 (ground).

Is the resistance reading less than the specified value?

1 V

Go to Integrity Check

Go to Step 10

10

Repair a short to voltage condition in CKT 348.

Are the repairs complete?

--

Go to Step 11

--

11

Reconnect all the SIR system components, make sure all the components are properly mounted.

Have all the SIR components been reconnected and properly mounted?

--

Go to Step 12

--

12

Clear all the SIR DTCs.

Have all the SIR DTCs been cleared?

--

Go to SIR Diagnostic System Check

--