GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2000 🢒 GMC K Sierra - 4WD 🢒 DTC 🢒 DTC B0026 LF/Driver Frontal Deployment Loop (Single Stage or Stage 1) Open

Object Number: 542841 Size: SF
SIR Components
SIR Schematics Pickup
SIR Handling Caution
Handling ESD Sensitive Parts Notice
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 to diagnose critical malfunctions within itself. The SDM then 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 Running the DTC
    • 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.

Conditions for Setting the DTC
    • The SDM detects the driver frontal deployment loop resistance is greater than 4.8 ohms for 300 milliseconds.
    • The SDM detects the voltage at driver frontal high is less than 2.4 volts and driver frontal high to low side resistance is 6 ohms or greater for 300 milliseconds.

Action Taken When the DTC Sets
    • The SDM commands ON the AIR BAG warning lamp via Class 2 serial data.
    • The SDM also sets this DTC as current after an accident. The SDM will write the status of this DTC to the "crash log" area of the EEPROM for retrieval.

Conditions for Clearing the DTC
    • Driver frontal high deployment loop resistance is 4.8 ohms or greater for 300 milliseconds.
    • Driver frontal high is greater than 2.4 volts and driver frontal deployment loop resistance is less than 6 ohms for 300 milliseconds.
    • You issue a scan tool CLEAR CODES command.
    • A history DTC will clear once 255 malfunctions free ignition cycles have occurred.

When the SDM detects that no DTCs are present, the SDM commands the AIR BAG warning lamp OFF.

Diagnostic Aids

The following can cause an intermittent condition:

    • A short between the driver frontal high and the driver frontal low circuits.
    • A malfunctioning shorting bar on the inflatable restraint steering wheel module 2-way connector.
    • A malfunctioning shorting bar on the inflatable restraint steering wheel module coil 2-way connector.
    • Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Test Description

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

  1. This step inspects the driver inflator module in-line connector below the inflatable restraint steering wheel module coil.

    2.

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

    3.

  3. This step checks to see if the inflatable restraint sensing and diagnostic module (SDM) wiring harness connector is OK.

    4.

  4. Tests for an open or a high resistance in the driver frontal high circuit.

    5.

  5. Tests for an open or a high resistance in the driver frontal low circuit or if there is a malfunctioning SDM.

Step

Action

Value(s)

Yes

No

1

Did you perform the SIR Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - SIR

2

  1. Turn OFF the ignition.
  2. Disconnect the in-line connector that connects the inflatable restraint steering wheel module coil to the vehicle wiring harness.
  3. Inspect both wiring harness connectors 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 wiring harness side of the in-line connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
  2. If the inflatable restraint steering wheel module coil exhibits any of the above conditions, the module must be replaced. Refer to Inflatable Restraint Steering Wheel Module Coil Replacement .

Did you complete the replacement?

--

Go to Step 16

--

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. Use the scan tool to 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 in-line connector below the inflatable restraint steering wheel module coil.
  3. Install the J 38715-A SIR Load Tool to the vehicle wiring harness side of the in-line connector. Use the appropriate wiring harness connector adaptors where necessary.
  4. Turn ON the ignition, with the engine OFF.
  5. Use the scan tool to request the SIR DTC display.

Does the scan tool indicate that DTC B0026 is current?

--

Go to Step 9

Go to Step 6

6

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

Does the scan tool indicate that DTC B0026 is current?

--

Go to Step 8

Go to Step 7

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

Did you complete the replacement?

--

Go to Step 16

--

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

Did you complete the replacement?

--

Go to Step 16

--

9

  1. Turn OFF the ignition.
  2. Disconnect the inflatable restraint sensing and diagnostic module (SDM) wiring harness connector. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  3. Disconnect the J 38715-A SIR Load Tool.
  4. Check for proper connections at the driver frontal high terminal and the driver frontal low terminal of the inflatable restraint sensing and diagnostic module (SDM) wiring harness connector.

Is the inflatable restraint sensing and diagnostic module (SDM) wiring harness connector OK?

--

Go to Step 11

Go to Step 10

10

Replace the inflatable restraint sensing and diagnostic module (SDM) wiring harness connector. Refer to Connector Repairs in Wiring Systems.

Did you complete the replacement?

--

Go to Step 16

--

11

Using J 39200 DMM measure the resistance between the driver frontal high deployment circuit of the in-line connector and the inflatable restraint sensing and diagnostic module (SDM) wiring harness connector. Refer to Circuit Testing in Wiring Systems.

Does the resistance measure within the specified value?

0-0.5 ohms

Go to Step 13

Go to Step 12

12

Locate and repair an open or high resistance in the driver frontal high circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 16

--

13

Using J 39200 DMM measure the resistance between the driver frontal low deployment circuit of the in-line connector and the inflatable restraint sensing and diagnostic module (SDM) wiring harness connector. Refer to Circuit Testing in Wiring Systems.

Does the resistance measure within the specified value?

0-0.5 ohms

Go to Step 15

Go to Step 14

14

Locate and repair an open or high resistance in the driver frontal low circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 16

--

15

Replace the inflatable restraint sensing and diagnostic module (SDM). Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .

Did you complete the replacement?

--

Go to Step 16

--

16
  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