GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 1999 🢒 Century (China) (CNG) 🢒 Restraints 🢒 SIR 🢒 DTC B0026 LF/Driver Frontal Deployment Loop (Single Stage or Stage 1) Open

Object Number: 369425 Size: SF
SIR Components
SIR Schematics
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. Then the SDM performs the following continuous diagnostic tests on the deployment loops:

    • Deployment loop voltage out of range test
    • Deployment loop resistance measurement test

If the voltage out of range test detects a short to voltage condition, the resistance measurement test for that deployment loop will not be performed.

Conditions for Setting the DTC
    • Deployment loop voltage out of range test.
       - Ignition 1 voltage is within the normal operating voltage range.
       - Driver frontal deployment loop is not shorted to voltage.
       - Driver frontal high terminal A6 is less than 2 volts.
       - Driver frontal deployment loop resistance is at least 6 ohms for 300 milliseconds.
    • Deployment loop resistance measurement test.
       - Ignition 1 voltage is within the normal operating voltage range.
       - Driver frontal deployment loop is not shorted to voltage.
       - Driver frontal deployment loop is not shorted to ground.
       - Driver frontal deployment loop resistance is more than 4.8 ohms for 300 milliseconds.

The driver frontal deployment loop consists of the following components:

    • Inflatable restraint steering wheel module.
    • Inflatable restraint steering wheel module coil.
    • Harness wiring of CKT 347.
    • Harness wiring of CKT 348.
    • Connector terminal contact.

Action Taken When the DTC Sets
    • The SDM sets a DTC B0026.
    • The SDM commands ON the AIR BAG warning lamp via Class 2 serial data.

Conditions for Clearing the DTC
    • Current DTC
       - Deployment loop voltage out of range test-Driver frontal high terminal A6 is more than 2 volts AND driver frontal deployment loop resistance is less than 6 ohms for 300 milliseconds.
       - Deployment loop resistance measurement test-Driver frontal deployment loop resistance is no more than 4.8 ohms for 300 milliseconds.
    • History DTC
       - You issue a scan tool CLEAR CODES command.
       - Once 250 malfunction free ignition cycles have occurred.

Diagnostic Aids

A poor connection can cause an intermittent condition. Check the following for a poor connection:

    • The inflatable restraint steering wheel module 2-way connector terminal A and terminal B.
    • The inline connector C215.
    • The SDM terminal A6 and terminal A7.
    • The wire to terminal connections in CKT 347.
    • The wire to terminal connections in CKT 348.

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

  1. This step checks the inline connector C215.

    2.

  2. This step determines if the inflatable restraint steering wheel module coil or if the inflatable restraint steering wheel module is defective.

    3.

  3. This step checks to see if the SDM wiring harness connector is OK.

    4.

  4. This step checks to see if there is an open or a high resistance in CKT 347.

    5.

  5. This step determines if there is an open or a high resistance in CKT 348 or if there is a malfunctioning SDM.

DTC B0026 Driver Frontal 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. Disconnect inline connector C215.
  3. Check the wiring harness side of inline connector C215 for corrosion or damaged terminals.

Is the wiring harness connector OK?

--

Go to Step 4

Go to Step 3

3

Replace the wiring harness side of inline connector C215. Refer to Wiring Repair .

Is the repair complete?

--

Go to Step 16

--

4
  1. Reconnect inline connector C215.
  2. Make sure that the connector position assurance (CPA) is properly installed.
  3. Turn the ignition switch to the RUN position.
  4. Use the scan tool to request the SIR DTC display.

Is DTC B0026 current?

--

Go to Step 5

Go to Step 3

5
  1. Turn the ignition switch to the OFF position.
  2. Disconnect inline connectors C215 and C216.
  3. Install the J 38715-A SIR Driver/Passenger Load Tool to the wiring harness side of inline connectors C215 and C216. Use the J 38715-5 adaptor for inline C216 and the J 38715-90 adaptor for inline connector C215.
  4. Turn the ignition switch to the RUN position.
  5. Use the scan tool to request the SIR DTC display.

Is DTC B0026 current?

--

Go to Step 9

Go to Step 6

6

  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 inline connector C215.
  4. Connect inline connector C215 back together.
  5. Connect the J 38715-A to the upper inflatable restraint steering wheel module coil connector on the steering column. Use the J 38715-30 adaptor for the upper coil connector.
  6. Turn the ignition switch to the RUN position.
  7. Use the scan tool to request the SIR DTC display.

Is DTC B0026 current?

--

Go to Step 8

Go to Step 7

7
  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 16

--

8
  1. Turn the ignition switch to the OFF position.
  2. Replace the inflatable restraint steering wheel module coil. Refer to Inflatable Restraint Steering Wheel Module Coil Replacement .

Is the repair complete?

--

Go to Step 16

--

9

  1. Turn the ignition switch to the OFF position.
  2. Remove the J 38715-A .
  3. Disconnect the inflatable restraint sensing and diagnostic module (SDM). Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  4. Check for proper connections at terminal A6 and terminal A7 of the SDM wiring harness connector.

Is the SDM wiring harness connector OK?

--

Go to Step 11

Go to Step 10

10

Replace the SDM wiring harness connector. Refer to Wiring Repair .

Is the repair complete?

--

Go to Step 16

--

11

  1. Zero the J 39200 Digital Multimeter (DMM).
  2. Use the J 39200 to measure the resistance between terminal A of inline connector C215 and terminal A6 of the SDM wiring harness connector.

Is the measured resistance within the specified value?

0-0.5 ohms

Go to Step 13

Go to Step 12

12
  1. Locate an open or a high resistance in CKT 347.
  2. Repair the open or the high resistance in CKT 347.

Is the repair complete?

--

Go to Step 16

--

13

Use the J 39200 to measure the resistance between terminal B of inline connector C215 and terminal A7 of the SDM wiring harness connector.

Is the measured resistance within the specified value?

0-0.5 ohms

Go to Step 15

Go to Step 14

14
  1. Locate an open or a high resistance in CKT 348.
  2. Repair the open or the high resistance in CKT 348.

Is the repair complete?

--

Go to Step 16

--

15

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

Is the repair complete?

--

Go to Step 16

--

16
  1. Reconnect all SIR components.
  2. Make sure that all components and connectors are properly mounted.
  3. Turn the ignition switch to the RUN position.
  4. Use the scan tool to clear all current and history SIR DTCs.

Have all current and history SIR DTCs been cleared?

--

Go to SIR Diagnostic System Check

--