GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 1999 🢒 Park Avenue 🢒 Restraints 🢒 SIR 🢒 DTC B1125 Driver/Pass Deploy Loop Short to Voltage

Object Number: 397197 Size: MF
SIR Components
SIR System Operation
SIR Handling Caution
Handling ESD Sensitive Parts Notice
SIR Schematic Icons
SIR Schematic Icons
SIR Schematic Icons

Circuit Description

When you first turn the ignition switch to the RUN position, the inflatable restraint sensing and diagnostic module (SDM) performs tests in order to diagnose critical malfunctions within the module. Upon passing these tests, the ignition positive voltage, 23 VLR and the deployment loop voltages are measured in order to ensure that the voltages are within the respective normal voltage ranges. The SDM monitors the voltages at the DRIVER LOW terminal 9 and the PASSENGER LOW terminal 8 in order to detect shorts to voltage in the inflator module circuits.

Conditions for Setting the DTC

The voltage at DRIVER LOW terminal 9 or the PASSENGER LOW terminal 8 is more than 4.0 volts for 500 milliseconds.

The following tests inspects for this DTC. These tests occur when ignition positive voltage is within the normal operating voltage range.

    • POWER-ON
        When 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 commands the instrument cluster to turn ON the AIR BAG warning lamp.

Conditions for Clearing the MIL/DTC
    • The voltage measured at the DRIVER LOW and the PASSENGER LOW is below 4.0 volts for 500 milliseconds.
    • The ignition switch is turned OFF.
    • DTC B1171 will remain CURRENT.

Diagnostic Aids

A short-to-voltage in the inflatable restraint steering wheel module circuit or the passenger inflator module circuit may cause an intermittent condition. Moving wires while monitoring the DRIVER SENSELO and the PASSENGER SENSELO may help locate the fault. Carefully inspect the following circuits for cutting or chafing:

    • CKT 347
    • CKT 348
    • CKT 1403
    • CKT 1404

The diagnostic table directs the technician to note the entry value of the DRIVER SENSELO and the PASSENGER SENSELO. Noting the value of the DRIVER SENSELO and the PASSENGER SENSELO during diagnosis may be helpful in determining if an intermittent condition exists.

When measurements are requested in this table, use the J 39200 DMM with the correct terminal adapter from the J 35616 Connector Test Adapter Kit. When an inspection for proper connection is requested, refer to Testing for Electrical Intermittents in Wiring Systems. When a wire, connector or terminal repair is requested, use the J-38125 Terminal Repair Kit and refer to Wiring Repairs in Wiring Systems.

Test Description

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

  1. This test determines the driver low voltage measured by the inflatable restraint sensing and diagnostic module (SDM) and if the malfunction is occurring now.

    2.

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

    3.

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

    4.

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

    5.

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

    6.

  6. This test isolates the malfunction to one side of the inflatable restraint IP module, yellow 2-way connector.

    7.

  7. This test determines whether the malfunction is in CKT 1403.

    8.

  8. This test determines whether the malfunction is in CKT 1404.

Step

Action

Value(s)

Yes

No

Notice: When DTC B1125 has been set it is necessary to replace the inflatable restraint Sensing and Diagnostic Module (SDM). Setting DTC B1125 will also cause DTC B1171 to set. When a scan tool clear codes command is issued and the malfunction is no longer present, DTC B1171 will remain current. Make sure that the short to voltage condition is repaired prior to installing a replacement SDM to avoid damaging the SDM.

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 low voltage DRIVER SENSELO.

Is the DRIVER SENSELO more than the specified value?

4.0 V

Go to Step 3

Go to Step 17

3

  1. Turn the ignition switch to the OFF position.
  2. Disconnect the inflatable restraint steering wheel module, yellow 2-way connector located near the base of the steering column. Leave the inflatable restraint IP module connected.
  3. Connect the J 38715-A to the inflatable restraint steering wheel module harness connector.
  4. Turn the ignition switch to the RUN position.
  5. Use the scan tool in order to request the SIR data list display and read the driver frontal low voltage DRIVER SENSELO.

Is the DRIVER SENSELO more than the specified value?

4.0 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 Steering Wheel Module Replacement .
  3. Disconnect the J 38715-A from the driver 2-way harness connector.
  4. Connect the driver 2-way connector.
  5. Connect the J 38715-A to the upper inflatable restraint steering wheel module connector.
  6. Turn the ignition switch to the RUN position.
  7. Use the scan tool in order to request the SIR data list display.
  8. Read the driver side low voltage DRIVER SENSELO.

Is the DRIVER SENSELO more than the specified value?

4.0 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 .

Is the repair complete?

--

Go to Step 18

--

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 .

Is the repair complete?

--

Go to Step 18

--

7
  1. Turn the ignition switch to the OFF position.
  2. Disconnect the inflatable restraint IP module, yellow 2-way connector located above the right side of the sound insulator.
  3. Disconnect the inflatable restraint sensing and diagnostic module (SDM).
  4. Disconnect J 38715-A .
  5. Turn the ignition switch to the RUN position.
  6. Measure the voltage on the SDM harness connector from terminal 10 to terminal 18 (ground).

Is the voltage reading 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. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 18

--

9

Measure the voltage on the SDM harness connector from terminal 9 to terminal 18 (ground).

Is the voltage reading less than the specified value?

1 V

Go to Step 11

Go to Step 10

10

Repair a short-to-voltage condition in CKT 348. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 18

--

11
  1. Turn the ignition switch to the OFF position.
  2. Disconnect the inflatabIe restraint IP module yellow 2-way connector above the right side of the sound insulator. Leave the inflatable restraint steering wheel module connected.
  3. Connect the J 38715-A to the IP module harness connector.
  4. Turn the ignition switch to the RUN position.
  5. Use the scan tool in order to request the SIR data list display.
  6. Read the passenger frontal low voltage PASSENGER SENSELO.

Is the PASSENGER SENSELO more than the specified value?

4.0 V

Go to Step 13

Go to Step 12

12
  1. Turn the ignition switch to the OFF position.
  2. Inspect the inflatable restraint IP module pigtail for damage and proper routing.
  3. Replace the inflatable restraint IP module. Refer to Inflatable Restraint Instrument Panel Module Replacement .

Is the repair complete?

--

Go to Step 18

--

13
  1. Turn the ignition switch to the OFF position.
  2. Disconnect the inflatable restraint steering wheel module, yellow 2 way connector located near the base of the steering column.
  3. Disconnect the inflatable restraint sensing and diagnostic module (SDM).
  4. Disconnect the J 38715-A .
  5. Measure the voltage on the SDM harness connector from terminal 8 to terminal 18 (ground).

Is the voltage less than the specified value?

1 V

Go to Step 15

Go to Step 14

14

Repair a short-to-voltage condition in CKT 1404. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 18

--

15

Measure the voltage on the SDM harness connector from terminal 7 to terminal 18 (ground).

Is the voltage less than the specified value?

1 V

Go to Sensing and Diagnostic Module Integrity Check

Go to Step 16

16

Repair a short-to-voltage condition in CKT 1403. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Step 18

--

17

An intermittent short-to-voltage condition caused DTC B1125 to set. Use the Diagnostic Aids for DTC B1125 and this table in order to find the intermittent short to voltage.

Has the intermittent short to voltage been found and repaired?

--

Go to Step 18

--

18
  1. Reconnect all the SIR system components. Ensure that all the components are properly mounted.
  2. Turn the ignition switch to the RUN position.
  3. Ensure that the DRIVER SENSELO and PASSENGER SENSELO are less than the specified value.
  4. Replace the inflatable restraint sensing and diagnostic module (SDM). Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .

Have all the SIR components been reconnected and properly mounted?

4.0 V

Go to SIR Diagnostic System Check

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