B1771
DTC B1771
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 B1771
- Passenger Seat Belt Sensor Circuit
Circuit/System Description
The seat belt buckle switch circuit consists of a seat belt buckle switch and the sensing and diagnostic module (SDM). The SDM monitors the seat belt buckle switch for a buckled/unbuckled state. If the SDM detects a malfunction within the seat belt buckle switch circuit, a DTC will be set.
Conditions for Running the DTC
Ignition voltage is between 9-16 volts.
Conditions for Setting the DTC
Any of the following conditions exist for 2 seconds:
B1771
* The passenger seat belt buckle circuit is shorted.
* The passenger seat belt buckle circuit is open.
* Passenger seat belt buckle malfunction.
* Occupant classification module malfunction.
Action Taken When the DTC Sets
* The SDM commands the AIR BAG indicator ON.
* The SIR System is disabled and no deployments are allowed.
Conditions for Clearing the DTC
* The condition for setting the DTC no longer exists.
* A history DTC will clear once 100 malfunction-free ignition cycles have occurred.
Reference Information
Schematic Reference
SIR Schematics ([1][2]Air Bag Systems)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
SIR 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)
* Connector Repairs (Connector Repairs)
* Wiring Repairs (Wiring Repairs)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information.
Circuit/System Testing
Important: Refer to SIR Service Precautions (Technician Safety Information).
When removing connectors, inspect for damage or corrosion. Damage or corrosion in the following requires repair or replacement of the affected component/connector:
* The front end sensor
* The SDM module
* The front end sensor wiring harness connector
* The SDM wiring harness connector
1. Ignition OFF, disconnect the harness connector at the SDM and the appropriate sensor.
2. Ignition ON, test for less than 1 volt between the signal circuit terminal 13 and ground.
• If greater than the specified range, repair the circuit for a short to voltage.
3. Ignition ON, test for less than 1 volt between the low reference circuit terminal 14 and ground.
• If greater than the specified range, repair the circuit for a short to voltage.
4. Test for infinite resistance between the signal circuit terminal 13 and ground.
• If less than infinite resistance, repair the circuit for a short to ground.
5. Test for less than 1 ohm between front inner seat belt assembly - passenger terminal 2 and SDM harness connector terminal 13.
• If greater than the specified range, repair the circuit for an open/high resistance.
6. Test for less then 1 ohm between front inner seat belt assembly - passenger terminal 1 and SDM harness connector terminal 14.
• If greater than the specified range, repair the circuit for an open/high resistance.
7. If all circuits test normal, replace the passenger seat belt buckle assembly.
8. Reconnect all SIR components. Ignition ON, with a scan tool clear and check for DTCs.
• If the DTC returns and is current, replace the occupant classification module.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Inflatable Restraint Front End Sensor Replacement (Inflatable Restraint Front End Sensor Replacement)
* Inflatable Restraint Side Impact Sensor Replacement (Front) (Inflatable Restraint Side Impact Sensor Replacement (Front))Inflatable Restraint Side Impact Sensor Replacement (Rear) (Inflatable Restraint Side Impact Sensor Replacement (Rear))
* SIR/SRS Wiring Repairs (SIR/SRS Wiring Repairs)
* Control Module References (Programming and Relearning) for SDM replacement, setup, and programming