SAAB WIS ONLINE

DTC B0072

DTC B0072

Diagnostic Instructions


• Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• Diagnostic Procedure Instructions provides an overview of each diagnostic category


DTC Descriptors

DTC B0072 01

Driver Seat Belt Switch Circuit Short to Battery

DTC B0072 02

Driver Seat Belt Switch Circuit Short to Ground

DTC B0072 04

Driver Seat Belt Switch Circuit Open

DTC B0072 06

Driver Seat Belt Switch Circuit Low Voltage/Open

DTC B0072 08

Driver Seat Belt Switch Circuit Performance - Signal Invalid

DTC B0072 0B

Driver Seat Belt Switch Circuit High Current

DTC B0072 0C

Driver Seat Belt Switch Circuit Low Current

Diagnostic Fault Information

Circuit Short to Ground Open/High Resistance Short to Voltage Signal Performance
Driver Seat Belt Sensor Control

B0072 02, B0072 0B

B0072 04, B0072 06

B0072 01

B0072 08



Circuit/System Description

The inflatable restraint seat belt buckle switch is within the seat belt buckle and provides an input to the inflatable restraint sensing and diagnostic module (SDM). The SDM supplies a low reference circuit and a seat belt switch signal circuit to determine a buckled or unbuckled condition. The SDM monitors the seat belt switch circuits and if a fault is detected a DTC will be set.

Conditions for Running the DTC

Ignition voltage is between 9-16 V.

Conditions for Setting the DTC

B0072 01

The driver seat belt switch circuit is shorted to voltage.

B0072 02

The driver seat belt switch circuit is shorted to ground.

B0072 04

The driver seat belt switch circuit is open.

B0072 06

The driver seat belt switch circuit is shorted to ground or open.

B0072 08

The driver seat belt switch signal is invalid.

B0072 0B

The driver seat belt switch signal is above threshold.

B0072 0B

The driver seat belt switch signal is below threshold.

Action Taken When the DTC Sets

The SDM will store a DTC and illuminate the Air Bag indicator in the instrument cluster.

Conditions for Clearing the DTC

The condition responsible for setting the DTC no longer exists.

Reference Information

Schematic Reference

SIR Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

SIR System Description and Operation

Electrical Information Reference


• Circuit Testing

• Testing for Intermittent Conditions and Poor Connections

• Wiring Repairs

• Connector Repairs


Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Ignition ON, observe the scan tool Driver Seat Belt Status parameter while buckling and unbuckling the seat belt. The reading should be Unbuckled when the seat belt is unbuckled and the reading should be Buckled when the seat belt is buckled.

Circuit/System Testing

Warning

When performing service on or near the SIR components or the SIR wiring, the SIR system must be disabled. Refer to SIR Disabling and Enabling. Failure to observe the correct procedure could cause deployment of the SIR components, personal injury, or unnecessary SIR system repairs.


For additional information about the SIR Precautions refer to SIR Service Precautions .


• Air bag module

• SDM module

• Air bag wiring harness connector

• SDM wiring harness connector



1. Ignition OFF, disconnect the X1 and X3 harness connector at the K36 Inflatable Restraint Sensing and Diagnostic Module and the harness connector at the B88D Seat Belt Switch - Driver.

2. Ignition ON, test for less than 0.3 V between the B88D Seat Belt Switch - Driver harness connector terminal 1 and ground.

3. If greater than the specified range, test the circuit for a short to voltage.

4. Test for less than 0.3 V between the B88D Seat Belt Switch - Driver harness connector terminal 2 and ground.

5. If greater than the specified range, test the circuit for a short to voltage.

6. Ignition OFF, test for infinite resistance between the B88D Seat Belt Switch - Driver harness connector terminal 1 and ground.

7. If less than the specified value, test the circuit for a short to ground.

8. Test for infinite resistance between the B88D Seat Belt Switch - Driver harness connector terminal 2 and ground.

9. If less than the specified value, test the circuit for a short to ground.

10. Test for less than 1 Ω between the K36 Inflatable Restraint Sensing and Diagnostic Module harness connector terminal 41 X3i and B88D Seat Belt Switch - Driver harness connector terminal 1.

11. If greater than the specified range, test the circuit for an open/high resistance.

12. Test for less than 1 Ω between the K36 Inflatable Restraint Sensing and Diagnostic Module harness connector terminal 43 X3 and B88D Seat Belt Switch - Driver harness connector terminal 2.

13. If greater than the specified range, test the circuit for an open/high resistance.

14. If all circuits test normal, replace the B88D Seat Belt Switch - Driver. If the DTC resets, replace the K36 Inflatable Restraint Sensing and Diagnostic Module.


Component Testing


Static Test

1. Ignition OFF, disconnect the harness connector at the B88D Seat Belt Switch - Driver.

2. Test for less than 10 Ω between the B88D Seat Belt Switch - Driver connector terminal 1 and terminal 2.

3. If greater than the specified value, replace the B88D Seat Belt Switch - Driver.

4. Fasten the driver seat belt.

5. Test for more than 200 Ω between the B88D Seat Belt Switch - Driver connector terminal 1 and terminal 2.

6. If less than the specified value, replace the B88D Seat Belt Switch - Driver.


Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.


• Driver or Passenger Seat Belt Buckle Replacement

• SIR/SRS Wiring Repairs

• Control Module References for SDM replacement, setup, and programming