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 on. 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 hard wire to the instrument panel multifunction switch. After receiving the message, the instrument panel multifunction switch 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 Control Module References for scan tool information
Circuit/System Verification
1. Ignition ON.
2. Have someone sit in the passenger seat.
3. With a scan tool verify the Passenger Seat Occupancy Status indicates Occupied.
• If the Passenger Seat Occupancy Status does not indicate Occupied
• Replace the passenger presence sensor.
• If the Passenger Seat Occupancy Status does indicate Occupied
4. Ignition ON.
5. With a scan tool perform the Passenger Seat Belt Reminder Indicator On/Off Control Function and verify the passenger seat belt indicator turns on and off.
• If the passenger seat belt indicator does not turn on and off
• Refer to Seat Belt Indicator Malfunction.
• If the passenger seat belt indicator does turn on and off
6. With the scan tool monitor the Passenger Seat Belt Status parameter while buckling and unbuckling the seat belt. The parameter should display Buckled and Unbuckled when buckling and unbuckling the seat belt.
• If the Passenger Seat Belt Status parameter does not display Buckled and Unbuckled when buckling and unbuckling the seat belt.
• Refer to Seat Belt Switch Malfunction.
• If the Passenger Seat Belt Status parameter does display Buckled and Unbuckled when buckling and unbuckling the seat belt.
Circuit/System Testing
Seat Belt Switch Malfunction
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.
2. Disconnect the harness connector at the B88 passenger seat belt switch.
3. Test for less than 5 ohm between the low reference circuit terminal 2 and ground.
• If 5 ohm or greater
1. Disconnect the harness connector at the K36 SDM.
2. Test for less than 2 ohm in the low reference circuit end to end.
• If 2 ohm or greater, repair the open/high resistance in the circuit.
• If less than 2 ohm, replace the K36 SDM.
• If less than 5 ohm
4. Ignition ON.
5. Verify the scan tool Passenger Seat Belt Status parameter displays Buckled.
• If the scan tool Passenger Seat Belt Status parameter does not display Buckled
1. Disconnect the harness connector at the K36 SDM.
2. Test for infinite resistance between the seat belt switch signal circuit terminal 2 and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If less than 2 ohm, replace the K36 SDM.
• If the scan tool Passenger Seat Belt Status parameter does display Buckled
6. Install a 3 A fused jumper wire between the signal circuit terminal 1 and the low reference circuit terminal 2.
7. Verify the scan tool Passenger Seat Belt Status parameter displays Unbuckled.
• If the scan tool Passenger Seat Belt Status parameter does not display Unbuckled
1. Disconnect the harness connector at the K36 SDM.
2. Ignition ON.
3. 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.
4. Test for less than 2 ohm in each circuit end to end.
• If 2 ohm or greater, repair the open/high resistance in the circuit.
• If less than 2 ohm, replace the K36 SDM.
• If the scan tool Passenger Seat Belt Status parameter does display Unbuckled
8. Replace the B88 seat belt switch.
Seat Belt Indicator Malfunction
1. Ignition OFF.
2. Disconnect the harness connector at the instrument panel multifunction switch.
3. Test for less than 5 ohm between the ground circuit terminal 1 and ground.
• If 5 ohm or greater
1. Disconnect the harness connector at the K36 SDM.
2. Test for less than 2 ohm in each control circuit end to end.
• If 2 ohm or greater, repair the open/high resistance in the circuit.
• If less than 2 ohm, replace the K36 SDM.
• If less than 5 ohm
4. Connect a test lamp between the control circuit terminal 4 and ground.
5. Ignition ON.
6. Command the Passenger Seat Belt Reminder Indicator ON and OFF with a scan tool, the test lamp should turn ON and OFF while changing between the commanded states.
• If the test lamp is always on
1. Ignition OFF.
2. Disconnect the harness connector at the K36 SDM.
3. Ignition ON.
4. Test for less than 1 V between the signal circuit and ground.
• If 1V or greater, repair the short to voltage on the circuit.
• If less than 1V, replace the K36 SDM.
• If the test lamp is always off
1. Disconnect the harness connector at the K36 SDM.
2. Test for infinite resistance between the seat belt switch signal circuit terminal 4 and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
3. Test for less than 2 ohm in each control circuit end to end.
• If 2 ohm or greater, repair the open/high resistance in the circuit.
• If less than 2 ohm, replace the K36 SDM.
• If test lamp turns on and off while changing between the commanded states
7. Replace the instrument panel multifunction switch.
Component Testing
1. Ignition OFF.
2. Disconnect the harness connector at the B88 passenger seat belt switch.
3. B88 seat belt switch in the open position.
4. Test for infinite resistance between the signal circuit terminal 1 and the low reference terminal 2, at the B88 passenger seat belt switch.
• If there is not infinite resistance
• Replace the B88 passenger seat belt switch.
• If there is infinite resistance
5. B88 seat belt switch in the closed position.
6. Test for less than 1 ohm between the signal circuit terminal 1 and the low reference terminal 2, at the B88 passenger seat belt switch.
• If 2 ohm or greater
• Replace the B88 passenger seat belt switch.
• If less than 2 ohm
7. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Front Seat Belt Buckle Replacement Front Seat Belt Buckle Replacement
* Inflatable Restraint Front Passenger Presence Sensor Replacement Service and Repair
* Instrument Panel Multifunction Switch Replacement Instrument Panel Multifunction Switch Replacement
* Control Module References Control Module References for SDM or instrument panel cluster replacement, setup, and programming