GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2002 🢒 Eldorado 🢒 Restraints 🢒 SIR 🢒 DTC B1126

Circuit Description

The driver deployment loop consists of an inflatable restraint steering wheel module, inflatable restraint steering wheel module coil, the steering wheel module high and steering wheel module low circuits. A shorting bar is used in the inflatable restraint steering wheel module connector which will short together the steering wheel module high and steering wheel module low circuits when the connector is disconnected, this will help to prevent unwanted deployment of the inflator module during servicing. During a frontal crash of sufficient force the inflatable restraint sensing and diagnostic module (SDM) will allow current to flow through the deployment loop in order to deploy the inflatable restraint steering wheel module. The SDM performs continuous diagnostic tests on the deployment loops to check for proper circuit continuity and for shorts to ground or voltage. If a malfunction is detected, a DTC will be stored in non-volatile memory.

Conditions for Running the DTC

Ignition 1 Voltage is within the normal operating voltage range.

Conditions for Setting the DTC

Steering wheel module deployment loop is greater than or equal to 426 millivolts for 500 milliseconds.

Steering wheel module deployment loop resistance is greater than or equal to 250 ohms for 500 milliseconds.

Action Taken When the DTC Sets

The SDM commands the AIR BAG warning indicator ON via Class 2 serial data.

Conditions for Clearing the DTC
    • The condition responsible for setting the DTC no longer exists and the scan tool Clear DTCs function is used.
    • A history DTC will clear once 255 malfunction free ignition cycles have occurred.

Diagnostic Aids

The following are possible causes of the malfunction:

    • The wire to terminal connections in the steering wheel module high and/or steering wheel module low circuit.
    • The steering wheel module wiring harness connector.
    • The steering wheel module coil wiring harness connector.
    • The SDM wiring harness connector.

Thoroughly inspect the wiring and the connectors. An incomplete inspection of the wiring and the connectors may result in a misdiagnosis, causing a part replacement with the reappearance of the malfunction. If an intermittent malfunction exists, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Test Description

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

  1. Tests to see if the malfunction is caused by the steering wheel module or by the steering wheel module coil.

    2.

  2. Tests for a open in the steering wheel module high and steering wheel module low circuits.

Step

Action

Yes

No

Schematic Reference: SIR Schematics

1

Did you perform A Diagnostic System Check - SIR?

Go to Step 2

Go to Diagnostic System Check - SIR

2
  1. Turn OFF the ignition.
  2. Disconnect the inflatable restraint steering wheel module coil in-line connector. Refer to Inflatable Restraint Steering Wheel Module Coil Replacement .
  3. Inspect the component and harness sides of the steering wheel module coil in-line connector for damage or corrosion that may cause a open in the high or low circuits. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Does the steering wheel module coil in-line connector exhibit any signs of damage or corrosion?

Go to Step 3

Go to Step 4

3
  1. If the steering wheel module coil in-line connector is damaged, the steering wheel module coil must be replace. Refer to Inflatable Restraint Steering Wheel Module Coil Replacement .
  2. If the wiring harness side of steering wheel module coil in-line connector is damaged, replace the harness side of the connector. Refer to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 11

--

4
  1. Install the J 38715-A SIR Driver/Passenger Load Tool BASE OF COLUMN connector to harness side of steering wheel module coil in-line connector.
  2. Turn ON the ignition, with the engine OFF.
  3. Use the scan tool to request SIR DTCs displayed.

Does the scan tool indicate that this DTC B1126 is current?

Go to Step 8

Go to Step 5

5

  1. Turn OFF the ignition.
  2. Disconnect the J 38715-A .
  3. Reconnect the steering wheel module coil in-line connector.
  4. Remove the inflatable restraint steering wheel module. Refer to Inflatable Restraint Steering Wheel Module Replacement .
  5. Use the J 38715-30 adaptor to connect the J 38715-A STEERING COLUMN connector to the upper steering wheel module coil connector on top of the steering column.
  6. Turn ON the ignition, with the engine OFF.
  7. Use the scan tool to request SIR DTCs displayed.

Does the scan tool indicate that this DTC B1126 is current?

Go to Step 6

Go to Step 7

6
  1. Turn OFF the ignition.
  2. Replace the steering wheel module coil. Refer to Inflatable Restraint Steering Wheel Module Coil Replacement .

Did you complete the replacement?

Go to Step 11

--

7
  1. Turn OFF the ignition.
  2. Replace the steering wheel module. Refer to Inflatable Restraint Steering Wheel Module Replacement .

Did you complete the replacement?

Go to Step 11

--

8
  1. Turn OFF the ignition.
  2. Disconnect the J 38715-A .
  3. Disconnect the inflatable restraint sensing and diagnostic module (SDM). Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  4. Inspect the SDM connector for damage or corrosion that may cause a open in the steering wheel module high and low circuits. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 11

Go to Step 9

9

Test the steering wheel module high and the steering wheel low circuits for a open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 11

Go to Step 10

10

Replace the SDM. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .

Did you complete the replacement?

Go to Step 11

--

11
  1. Use the scan tool in order to Clear the DTCs.
  2. 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