GM Service Manual Online
For 1990-2009 cars only

Object Number: 260337  Size: SF
SIR Components
SIR Schematics
Handling ESD Sensitive Parts Notice
SIR Caution
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. Next the SDM measures IGNITION voltage to make sure it is within its respective normal voltage range. Then the SDM proceeds with the DEPLOYMENT LOOP CONTINUITY test. During the DEPLOYMENT LOOP CONTINUITY test, the SDM measures the voltage difference between Driver Belt High and Driver Belt Low.

Conditions for Setting the DTC

    • The driver seat belt pretensioner deployment loop resistance is more than 500 ohms.
    • The malfunction must be present for at least 500 milliseconds during one of the following tests:
       - DEPLOYMENT LOOP CONTINUITY
       - If the malfunction is detected in this test, the RESISTANCE MEASUREMENT test will not be performed.
       - CONTINUOUS MONITORING

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 driver seat belt pretensioner deployment loop resistance is less than 100 ohms for 500 milliseconds.
    • History DTC
       - You issue a scan tool CLEAR CODES command.
       - Once 250 malfunction free ignition cycles have occurred.

Diagnostic Aids

The following can cause an intermittent condition:

    • A poor connection at the driver seat buckle side belt harness connector terminals A and B.
    • A poor connection at the SDM terminals 8 and 9.
    • An open in CKT 2118.
    • An open in CKT 2119.

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 deployment loop resistance measured by the inflatable restraint Sensing and Diagnostic Module (SDM).

  2. This test checks for proper contact or corrosion of the yellow 2-way connector.

  3. This test isolates the malfunction to one side of the driver seat buckle side belt yellow 2-way connector.

  4. This test checks for proper contact or corrosion of the SDM connector.

  5. This test determines whether the malfunction is in CKT 2118.

  6. This test determines whether the malfunction is in CKT 2119.

DTC B1042 LH Pretensioner Deployment Loop Open

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 side air bag deployment loop voltage difference LH PRETENSIONER VDIF.

Has LH PRETENSIONER VDIF 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 driver seat module and driver seat buckle side belt yellow 2-way connectors located under the driver seat.
  3. Check for proper connection at terminals A and B on the body harness side of the driver seat buckle side belt yellow 2-way connector (the larger of the two yellow 2-way body harness connectors).

Are the terminals damaged or corroded?

--

Go to Step 4

Go to Step 6

4

Replace the driver seat buckle side belt yellow 2-way body harness connector. Refer to Wiring Repair .

Are the repairs complete?

--

Go to Step 5

--

5

Check for proper connection at terminals A and B on the driver seat buckle side belt yellow 2-way connector.

Are the terminals damaged or corroded?

--

Go to Step 7

Go to Step 21

6

Check for proper connection at terminals A and B on the driver seat buckle side belt yellow 2-way connector.

Are the terminals damaged or corroded?

--

Go to Step 7

Go to Step 8

7

Replace the driver seat buckle side belt. Refer to Seat Buckle Side Belt Replacement .

Has the driver seat buckle side belt been replaced?

--

Go to Step 21

--

8

  1. Reconnect the inflatable restraint driver seat module and driver seat buckle side belt yellow 2-way connectors located under the driver seat.
  2. Turn the ignition switch to the RUN position.
  3. Using the scan tool, request the SIR data list display.
  4. Read the driver seat belt pretensioner deployment loop voltage difference LH PRETENSIONER VDIF.

Is LH PRETENSIONER VDIF more than the specified value?

480 mV

Go to Step 10

Go to Step 9

9

  1. Turn the ignition switch to the OFF position.
  2. Replace the driver seat buckle side belt yellow 2-way body harness connector. Refer to Wiring Repair .

Are the repairs complete?

--

Go to Step 21

--

10

  1. Turn the ignition switch to the OFF position.
  2. Disconnect the inflatable restraint front side impact module (LH) and driver seat buckle side belt yellow 2-way connectors located under the driver seat.
  3. Connect the J 38715-A SIR Driver/Passenger Load Tool STEERING WHEEL and PASSENGER INFLATOR connector to the yellow 2-way harness connectors.
  4. Turn the ignition switch to the RUN position.
  5. Using the scan tool, request the data list display.
  6. Read the driver side air bag deployment loop voltage difference LH PRETENSIONER VDIF.

Is LH PRETENSIONER VDIF more than the specified value?

480 mV

Go to Step 12

Go to Step 11

11

  1. Turn the ignition switch to the OFF position.
  2. Replace the driver seat buckle side belt. Refer to Seat Buckle Side Belt Replacement .

Has the driver seat buckle side belt been replaced?

--

Go to Step 21

--

12

  1. Turn the ignition switch to the OFF position.
  2. Disconnect the inflatable restraint Sensing and Diagnostic Module (SDM).
  3. Disconnect the J 38715-A .
  4. Check for proper connection at terminals 8 and 9 on the SDM harness connector.

Is the harness connector damaged or corroded?

--

Go to Step 13

Go to Step 15

13

Replace the SDM connector. Refer to Wiring Repair .

Are the repairs complete?

--

Go to Step 14

--

14

Check for proper connection at terminals 8 and 9 on the SDM.

Are the terminals damaged or corroded?

--

Go to Step 16

Go to Step 21

15

Check for proper connection at terminals 8 and 9 on the SDM.

Are the terminals damaged or corroded?

--

Go to Step 16

Go to Step 17

16

Replace the inflatable restraint Sensing and Diagnostic Module (SDM). Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .

Are the repairs complete?

--

Go to Step 21

--

17

  1. Zero the J 39200 Digital Multimeter.
  2. Measure the resistance from the SDM harness connector terminal 8 to the driver seat buckle side belt yellow 2-way harness connector terminal A.

Is the resistance reading within the specified values?

0-0.5 ohms

Go to Step 19

Go to Step 18

18

Repair the high resistance condition in CKT 2118.

Are the repairs complete?

--

Go to Step 21

--

19

  1. Zero the J 39200 .
  2. Measure the resistance from the SDM harness connector terminal 9 to the driver seat buckle side belt yellow 2-way harness connector terminal B.

Is the resistance reading within the specified values?

0-0.5 ohms

Go to Integrity Check

Go to Step 20

20

Repair the high resistance condition in CKT 2119.

Are the repairs complete?

--

Go to Step 21

--

21

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

Have all the SIR components been reconnected and properly mounted?

--

Go to Step 22

--

22

Clear all the SIR DTCs.

Have all the DTCs been cleared?

--

Go to SIR Diagnostic System Check

--