B0072
DTC B0072 or B0073
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category
DTC Descriptors
DTC B0072
- Driver Seat Belt Switch Circuit
DTC B0073
- Passenger Seat Belt Switch Circuit
For symptom byte information refer to Symptom Byte List Symptom Byte List.
Diagnostic Fault Information
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 inflatable restraint sensing and diagnostic module supplies a low reference circuit and a seat belt switch signal circuit to determine a buckled or unbuckled condition. The inflatable restraint sensing and diagnostic module 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 or B0073 01
The seat belt switch circuit is shorted to voltage.
B0072 02 or B0073 02
The seat belt switch circuit is shorted to ground.
B0072 04 or B0073 03
The seat belt switch circuit is open.
B0072 05 or B0073 05
The seat belt switch circuit is shorted to voltage or open.
B0072 06 or B0073 06
The seat belt switch circuit is shorted to ground or open.
B0072 08 or B0073 08
The seat belt switch signal is invalid.
B0072 0B or B0073 0B
The seat belt switch signal is above threshold.
B0072 0C or B0073 0C
The seat belt switch signal is below threshold.
Action Taken When the DTC Sets
The inflatable restraint sensing and diagnostic module will store a DTC and illuminate the air bag indicator in the instrument cluster.
Conditions for Clearing the DTC
The condition for setting the DTC no longer exists.
Reference Information
Schematic Reference
SIR Schematics [1][2]Air Bag Systems
Connector End View Reference
Component Connector End Views Sunshade - Left
Description and Operation
Supplemental Inflatable Restraint System Description and Operation Description and Operation
Electrical Information Reference
* Circuit Testing Circuit Testing
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
* Connector Repairs Connector Repairs
Scan Tool Reference
Control Module References Control Module References for scan tool information
Circuit/System Verification
1. Ignition ON.
2. Verify the appropriate scan tool Seat Belt Status parameter changes between Buckled and Unbuckled when the seat belt is buckled and unbuckled.
• If the parameter does not change
Refer to Circuit/System Testing.
• If the parameter changes
3. All OK.
Circuit/System Testing
Note: When removing connectors inspect for damage or corrosion. Damage or corrosion in the following requires repair or replacement of the affected component/connector.
* B153D Seat Belt Buckle-Driver
* B153P Seat Belt Buckle-Passenger
* K36 Inflatable Restraint Sensing and Diagnostic Module
1. Ignition OFF. Scan tool disconnected. Disconnect the harness connector at the appropriate B153 Seat Belt Buckle. It may take up to 2 min for all vehicle systems to power down.
2. Test for less than 5 ohms between the low reference circuit terminal 2 and ground.
• If 5 ohms or greater
1. Ignition OFF, disconnect the harness connector at the K36 Inflatable Restraint Sensing and Diagnostic Module.
2. Test for less than 2 ohms in the low reference circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K36 Inflatable Restraint Sensing and Diagnostic Module.
• If less than 5 ohms
3. Ignition ON.
4. Verify the appropriate scan tool Seat Belt Status parameter is Buckled.
• If not Buckled
1. Ignition OFF, disconnect the harness connector at the K36 Inflatable Restraint Sensing and Diagnostic Module.
2. Test for infinite resistance between the signal circuit terminal 1 and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the K36 Inflatable Restraint Sensing and Diagnostic Module.
• If Buckled
5. Install a 3 A fused jumper wire between the signal circuit terminal 1 and the low reference circuit terminal 2.
6. Verify the appropriate scan tool Seat Belt Status parameter is Unbuckled.
• If not Unbuckled
1. Ignition OFF, disconnect the harness connector at the K36 Inflatable Restraint Sensing and Diagnostic Module, ignition ON.
2. Test for less than 1 V between the signal circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V
3. Test for less than 2 ohms in the signal circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K36 Inflatable Restraint Sensing and Diagnostic Module.
• If Unbuckled
7. Test or replace the B153 Seat Belt Buckle.
Component Testing
1. Ignition OFF. Scan tool disconnected. Disconnect the harness connector at the appropriate B153 Seat Belt Buckle. It may take up to 2 min for all vehicle systems to power down.
2. Test for infinite resistance between the signal terminal 1 and the low reference terminal 2.
• If less than infinite resistance
Replace the B153 Seat Belt Buckle.
• If infinite resistance
3. Insert the seat belt into the buckle.
4. Test for less than 5 ohms between the signal terminal 1 and the low reference terminal 2.
• If 5 ohms or greater
Replace the B153 Seat Belt Buckle.
• If less than 5 ohms
5. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Front Seat Belt Buckle Replacement Front Seat Belt Buckle Replacement
* SIR/SRS Wiring Repairs SIR/SRS Wiring Repairs
* Control Module References Control Module References for inflatable restraint sensing and diagnostic module replacement, programming, and setup.