GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 1998 🢒 Seville 🢒 Restraints 🢒 SIR 🢒 DTC B1124 Driver/Pass. Deploy. Loop Short to GND

Object Number: 261351 Size: MF
SIR Components
SIR Schematics
SIR Handling Caution
Handling ESD Sensitive Parts Notice
SIR Schematic Icons
SIR Schematic Icons

Circuit Description

When you first turn the ignition switch to the ON position, the inflatable restraint sensing and diagnostic module (SDM) performs tests to diagnose critical malfunctions within itself. Upon passing these tests Ignition 1, 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 9 and Passenger Frontal Low terminal 8 to detect shorts to ground in the inflator module circuits.

Conditions for Setting the DTC

    • The driver and passenger frontal deployment loops are not open.
    • The voltage at Driver Frontal Low terminal 9 or Passenger Frontal Low terminal 8 is less than 2.2 volts for 500 milliseconds.

The following tests check for this DTC. These tests occur when Ignition 1 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 (IPC) to turn ON the AIR BAG warning lamp.

Conditions for Clearing the MIL/DTC
    • The voltage measured at Driver Frontal Low and Passenger Frontal Low is above 2.2 volts for 500 milliseconds.
    • The ignition switch is turned OFF.

Diagnostic Aids

A short-to-ground in the inflatable restraint steering wheel module circuit or the passenger inflator module circuit can cause an intermittent condition. Moving wires while monitoring Driver Frontal Senselo and Passenger Frontal Senselo may help to locate the fault. Inspect CKT 347, CKT 348, CKT 1403, and CKT 1404 carefully for cutting or chafing. The diagnostic table directs the technician to note the entry value of Driver Frontal Senselo and Passenger Frontal Senselo. Noting the value of Driver Frontal Senselo and Passenger Frontal Senselo during diagnosis 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 General Electrical Diagnosis Procedures in Wiring Systems. 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 Low voltage measured by the inflatable restraint sensing and diagnostic module (SDM) and if the malfunction is currently occurring.

    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 1404.

    8.

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

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 OFF.
  2. Connect a scan tool to the DLC.
  3. Turn the ignition switch to ON.
  4. Request the SIR data list display. Refer to Scan Tool Data List .
  5. Read and record on the repair order the Driver Frontal Senselo.

Is Driver Frontal Senselo less than the specified value?

2.2 V

Go to Step 3

Go to Step 17

3

  1. Turn the ignition switch OFF.
  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 Load Tool to the inflatable restraint steering wheel module harness connector.
  4. Turn the ignition switch to ON.
  5. Using the scan tool, request the SIR data list display. Refer to Scan Tool Data List .
  6. Read the Driver Frontal Senselo.

Is Driver Frontal Senselo less than the specified value?

2.2 V

Go to Step 7

Go to Step 4

4

  1. Turn the ignition switch OFF.
  2. Remove the inflatable restraint steering wheel module. Refer to Supplemental Restraint Steering Wheel Module Replacement .
  3. Disconnect the J 38715-A Load Tool from the driver 2-way harness connector.
  4. Connect the driver 2-way connector.
  5. Connect the J 38715-A Load Tool to the upper inflatable restraint steering wheel module coil connector on the steering column.
  6. Turn the ignition switch to ON.
  7. Using the scan tool, request the SIR data list display. Refer to Scan Tool Data List .
  8. Read the Driver Frontal Senselo.

Is Driver Frontal Senselo less than the specified value?

2.2 V

Go to Step 6

Go to Step 5

5
  1. Turn the ignition switch OFF
  2. Replace the inflatable restraint steering wheel module. Refer to Supplemental Restraint Steering Wheel Module Replacement .

Have the repairs been completed?

--

Go to Step 18

--

6
  1. Turn the ignition switch OFF.
  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 .

Have the repairs been completed?

--

Go to Step 18

--

7

  1. Turn the ignition switch OFF.
  2. Disconnect the inflatable restraint IP module, yellow 2-way connector located above the passenger side sound insulator.
  3. Disconnect the yellow side air bag/pretensioner connector located under each front seat.
  4. Disconnect the inflatable restraint sensing and diagnostic module (SDM).
  5. Disconnect the J 38715-A Load Tool.
  6. Using J 39200 DMM, measure the resistance on the SDM harness connector from terminal 10 to terminal 18.

Is the resistance reading less than the specified value?

OL

Go to Step 8

Go to Step 9

8

Repair the short to ground in CKT 347. Refer to Wiring Repair .

Have the repairs been completed?

--

Go to Step 18

--

9

Using J 39200 DMM, measure the resistance on the SDM harness connector from terminal 9 to terminal 18.

Is the resistance reading less than the specified value?

OL

Go to Step 10

Go to Step 11

10

Repair the short to ground in CKT 348. Refer to Wiring Repair .

Have the repairs been completed?

--

Go to Step 18

--

11

  1. Turn the ignition switch OFF.
  2. Disconnect the inflatable restraint IP module yellow 2-way connector above the passenger side sound insulator. Leave the inflatable restraint steering wheel module connected.
  3. Connect the J 38715-A Load Tool to the IP module harness connector.
  4. Turn the ignition switch to ON.
  5. Using the scan tool, request the SIR data list display. Refer to Scan Tool Data List .
  6. Read the Passenger Frontal Senselo.

Is Passenger Frontal Senselo less than the specified value?

2.2 V

Go to Step 13

Go to Step 12

12
  1. Turn the ignition switch OFF.
  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 .

Have the repairs been completed?

--

Go to Step 18

--

13

  1. Turn the ignition switch OFF.
  2. Disconnect the inflatable restraint IP module, yellow 2-way connector located above the passenger sound insulator.
  3. Disconnect the yellow side air bag/pretensioner connector located under each front seat.
  4. Disconnect the inflatable restraint sensing and diagnostic module (SDM).
  5. Disconnect the J 38715-A Load Tool.
  6. Using J 39200 DMM, measure the resistance on the SDM harness connector from terminal 8 to terminal 18.

Is the resistance less than the specified value?

OL

Go to Step 14

Go to Step 15

14

Repair the short to ground in CKT 1404. Refer to Wiring Repair .

Have the repairs been completed?

--

Go to Step 18

--

15

Using J 39200 DMM, measure the resistance on the SDM harness connector from terminal 7 to terminal 18.

Is the resistance less than the specified value?

OL

Go to Step 16

Go to Sensing and Diagnostic Module Integrity Check

16

Repair the short to ground in CKT 1403. Refer to Wiring Repair .

Have the repairs been completed?

--

Go to Step 18

--

17
  1. An intermittent short to ground condition caused DTC B1124 to set. Do not clear DTC B1124 (history or current) until the intermittent short to ground is found and repaired.
  2. Turn the ignition switch to OFF.
  3. Disable frontal SIR system. Refer to Disabling the SIR System .
  4. Remove the inflatable restraint steering wheel module. Refer to Supplemental Restraint Steering Wheel Module Replacement .
  5. Connect the J 38715-A Load Tool to the upper inflatable restraint steering wheel module coil connector on the steering column.
  6. Connect the J 38715-A Load Tool to the IP module harness connector.
  7. Connect the driver 2-way connector at the base of the steering column.
  8. Turn the ignition switch to ON.
  9. Use the Diagnostic Aids for DTC B1124 and this table to aid in finding the intermittent short to ground.

Has the intermittent short to ground been found and repaired?

--

Go to Step 18

--

18
  1. Reconnect all the SIR system components, make sure all the components are properly mounted.
  2. Turn the ignition switch to ON.
  3. Make sure that Driver Frontal Senselo and Passenger Frontal Senselo are more than the specified value.

Have all the SIR components been reconnected and properly mounted?

2.2 V

Go to SIR Diagnostic System Check

--