Diagnostic Instructions
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
Connector End View Reference
Component Connector End Views
Description and Operation
SIR System Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References
for scan tool information.
Circuit/System Testing
Important: Refer to
SIR Service Precautions
.
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 wiring harness connector |
| • | The SDM wiring harness connector |
- Ignition OFF, disconnect the harness connector at the SDM and the appropriate sensor.
- 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. |
- 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. |
- 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. |
- 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. |
- 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. |
- If all circuits test normal, replace the passenger seat belt buckle assembly.
- 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
after completing the diagnostic procedure.
