Seat Belt Indicator Circuit Malfunction - Passenger
Seat Belt Indicator Circuit Malfunction - Passenger
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.
Diagnostic Fault Information
Circuit/System Description
When an individual is sitting in the passenger seat the passenger presence sensor detects the individual. A signal to the SDM indicates a person is in the passenger seat. The SDM will turn the passenger seat belt indicator. The passenger seat belt switch is a 2-wire switch wired to the inflatable restraint sensing and diagnostic module (SDM) using a signal circuit and a low reference circuit. When the seat belt is unbuckled the switch is closed, and when the seat belt is buckled the switch is open. The SDM sends the status of the passenger seat belt via a message to the radio/hvac control. After receiving the message, the radio/hvac control head controls the illumination of the passenger seat belt indicator.
Reference Information
Schematic Reference
Seat Belt Schematics ([1][2]Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector End Views By Name)
Description and Operation
Seat Belt System Description and Operation (Description and Operation)
Electrical Information Reference
* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)
Scan Tool Reference
Control Module References (Programming and Relearning)for scan tool information
Circuit/System Verification
1. Ignition ON, have someone sit in the passenger seat. With a scan tool verify the Passenger Classification Status indicates small 1, small 2, or large.
• If the scan tool does not indicate any of these states, test the passenger presence sensor serial data circuit and the low reference circuit for an open or short. If the circuits test normal, replace the passenger presence sensor.
2. Ignition ON, with a scan tool perform the Radio/HVAC Control Indicator On/Off Control Function and verify the passenger seat belt indicator turns on and off.
• If the indicator does not illuminate, replace the radio/havc control.
3. With the scan tool monitor the Passenger Seat Belt Switch parameter while buckling and unbuckling the seat belt. The parameter should display Buckled and Unbuckled when buckling and unbuckling the seat belt. If the status does not change states refer to Circuit/System Testing below.
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.
* B88 Seat belt switch
* Seat belt switch harness connector
* K36 SDM
* SDM harness connector
1. Ignition OFF, disconnect the harness connector at the B88 passenger seat belt switch.
2. Ignition OFF, test for less than 5 ohm between the low reference circuit terminal B and ground.
• If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K36 SDM.
3. Ignition ON, verify the scan tool Passenger Seat Belt Switch parameter displays Buckled.
• If not the specified value, test the signal circuit for a short to ground. If the circuit tests normal replace the K36 SDM.
4. Install a 3 A fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B. Verify the scan tool Passenger Seat Belt Switch parameter displays Unbuckled.
• If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K36 SDM.
5. If all circuits test normal, replace the B88 seat belt switch. Refer to Front Seat Belt Buckle Replacement (Front Seat Belt Buckle Replacement).
Component Testing
1. Ignition OFF, disconnect the harness connector at the B88 seat belt switch.
2. Test for infinite resistance between the signal circuit terminal A and the low reference terminal B, at the switch, with the switch in the open position.
• If less than the specified value, replace the B88 seat belt switch. Refer to Front Seat Belt Buckle Replacement (Front Seat Belt Buckle Replacement)
3. Test for less than 15 ohm between the signal circuit terminal A and the low reference terminal B, at the switch, with the switch in the closed position.
• If greater than the specified range, replace the B88 seat belt switch. Refer to Front Seat Belt Buckle Replacement (Front Seat Belt Buckle Replacement)
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
Control Module References (Programming and Relearning)for Radio/HVAC Control, PPS Sensor, and SDM replacement, setup, and programming