GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2001 🢒 Yukon XL - 4WD 🢒 Restraints 🢒 SIR 🢒 DTC B0026

Circuit Description

The inflatable restraint steering wheel module deployment loop consists of a steering wheel module, steering wheel module coil, steering wheel module high signal circuit, and steering wheel module low signal circuit. Shorting bars are used on the steering wheel module connector as well as the steering wheel module coil connector which will short together the steering wheel module high and steering wheel module low signal circuits when the connector is disconnected. This will help to prevent unwanted deployment of the inflator module during servicing. When the ignition is turned ON, the inflatable restraint sensing and diagnostic module (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.

Conditions for Running the DTC

Ignition 1 voltage is within the normal operating voltage range.

Conditions for Setting the DTC
    • The SDM detects the steering wheel module deployment loop resistance is greater than 4.8 ohms for 500 milliseconds.
    • The SDM detects the voltage at steering wheel module high signal is less than 2.4 volts and steering wheel module high to steering wheel module low signal resistance is 6 ohms or greater for 500 milliseconds.

Action Taken When the DTC Sets

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

Conditions for Clearing the DTC
    • The condition responsible for setting the DTC no longer exists.
    • You issue a scan tool CLEAR DTCs command.
    • A history DTC will clear once 255 malfunction free ignition cycles have occurred.

Diagnostic Aids

The following can cause an intermittent condition:

    • A short between the steering wheel module high and steering wheel module low signal circuits
    • A malfunctioning shorting bar on the steering wheel module connector
    • A malfunctioning shorting bar on the steering wheel module coil connector

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. This step inspects the steering wheel module coil in-line connector.

    2.

  2. Tests for proper operation of the steering wheel module coil and/or steering wheel module.

    3.

  3. Tests for an open or high resistance in the steering wheel module high and steering wheel module low signal 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 steering wheel module coil in-line connector located at the base of the steering column.
  3. Inspect both halves of the connector for the following conditions:
    4. • Corrosion
    • Terminal damage
    • Poor connections/terminal tension

Do the connectors exhibit any signs of corrosion, terminal damage, or poor connections?

Go to Step 3

Go to Step 4

3
  1. Replace the harness side of the in-line connector. Refer to Connector Repairs in Wiring Systems.
  2. If the steering wheel module coil connector exhibits any of the above conditions, the coil must be replaced. Refer to Inflatable Restraint Steering Wheel Module Coil Replacement .

Did you complete the replacement?

Go to Step 12

--

4
  1. Reconnect the in-line connector.
  2. Verify that the connector position assurance (CPA) is properly installed.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, request the SIR DTC display.

Does the scan tool indicate that DTC B0026 is current?

Go to Step 5

Go to Diagnostic Aids

5
  1. Turn OFF the ignition.
  2. Disconnect the steering wheel module coil in-line connector located at the base of the steering column.
  3. Use the J 38715-100 adaptor to connect the J 38715-A SIR Load Tool to the harness side of the in-line connector.
  4. Turn ON the ignition, with the engine OFF.
  5. With a scan tool, request the SIR DTC display.

Does the scan tool indicate that DTC B0026 is current?

Go to Step 7

Go to Step 6

6

  1. Turn OFF the ignition.
  2. Disconnect the J 38715-A and adaptor.
  3. Reconnect the in-line connector.
  4. Remove the steering wheel module. Refer to Inflatable Restraint Steering Wheel Module Replacement .
  5. Use the J 38715-30A adaptor to connect the J 38715-A to the upper steering wheel module coil connector on the steering column.
  6. Turn ON the ignition, with the engine OFF.
  7. With a scan tool, request the SIR DTC display.

Does the scan tool indicate that DTC B0026 is current?

Go to Step 10

Go to Step 11

7
  1. Turn OFF the ignition.
  2. Disconnect the J 38715-A and adaptor.
  3. Disconnect the SDM connector. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  4. Inspect the SDM connector for corrosion or damage. 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 12

Go to Step 8

8

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

Did you find and correct the condition?

Go to Step 12

Go to Step 9

9

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

Did you complete the replacement?

Go to Step 12

--

10

Replace the steering wheel module coil. Refer to Inflatable Restraint Steering Wheel Module Coil Replacement .

Did you complete the replacement?

Go to Step 12

--

11

Replace the steering wheel module. Refer to Inflatable Restraint Steering Wheel Module Replacement .

Did you complete the replacement?

Go to Step 12

--

12
  1. Reconnect all SIR system components.
  2. Verify that all components, connectors and CPAs are properly mounted.
  3. Use the scan tool in order to clear the DTCs.
  4. 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