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Seat Belt Indicator Circuit Malfunction - Passenger

Seat Belt Indicator Circuit Malfunction - Passenger

Diagnostic Instructions


Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.


Diagnostic Fault Information

Circuit Short to Ground High Resistance Open Short to Voltage Signal Performance
Passenger Seat Belt Switch Signal 1 2 2 2 -
Passenger Seat Belt Switch Low Reference - 2 2 2 -
1. Indicator will remain ON with seat belt buckled. 2. Indicator will illuminate only for the bulb check.


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 enables the passenger seat belt indicator on when there is someone sitting in the passenger seat. 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 passenger air bag disable indicator. The passenger air bag disable indicator will then control the illumination of the passenger seat belt indicator.

Reference Information

Schematic Reference

Seat Belt Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Seat Belt System Description and Operation

Electrical Information Reference


Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs


Scan Tool Reference

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 Automatic Occupant Sensing Current Front Occupancy Status indicates Occupied.

Disconnect the harness connector at the K36 SDM.

Test for infinite resistance between the folowing circuits terminal and ground:

- Sensor signal circuit terminal

- Sensor low reference circuit terminal

Test for less than 2 Ω in each circuit end to end.

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.

6. Replace the inflatable restraint instrument panel module indicator.

7. Replace the inflatable restraint instrument panel module indicator.

8. 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.

9. Refer to Circuit/System Testing below.

10. Monitor the scan tool Passenger Seat Belt Switch parameter while connecting and disconnecting the seat belt switch connector. The parameter should display Buckled and Unbuckled when changing seat belt states. If the status does not change states refer to Circuit/System Testing below.

11. Refer to Circuit/System Testing below.

12. All OK.


Circuit/System Testing


Seat Belt Switch Malfunction

1. Ignition OFF.

2. Disconnect the harness connector at the appropriate B88 passenger seat belt switch.

3. Test for less than 5 Ω between the ground circuit terminal B and ground.

3.1. Disconnect the harness connector at the K36 SDM.

3.2. Test for less than 2 Ω in each control circuit end to end.

4. Ignition ON.

5. Verify the scan tool Passenger Seat Belt Status parameter listed below is Buckled.

5.1. Disconnect the harness connector at the K36 SDM.

5.2. Test for infinite resistance between the seat belt switch signal circuit terminal 2 and ground.

6. Install a 3 A fused jumper wire between the signal circuit terminal A and the ground circuit terminal B.

7. Verify the scan tool Passenger Seat Belt Status parameter is Unbuckled.

7.1. Disconnect the harness connector at the K36 SDM.

7.2. Ignition ON.

7.3. Test for less than 1 V between the signal circuit and ground.

7.4. Test for less than 2 Ω in each circuit end to end.

8. Replace the B88 passenger seat belt switch.



Seat Belt Indicator Malfunction

1. Ignition OFF.

2. Disconnect the harness connector at the P14 passenger air bag disable indicator.

3. Test for less than 5 Ω between the ground circuit terminal 2 and ground.

3.1. Disconnect the harness connector at the K36 SDM.

3.2. Test for less than 2 Ω in each control circuit end to end.

4. Connect a test lamp between the control circuit terminal 5 and ground.

5. Ignition ON.

6. Command the Passenger Seat Belt Reminder ON and OFF with the scan tool. The test lamp should turn ON and OFF while changing between the commanded states.

6.1. Ignition OFF.

6.2. Disconnect the harness connector at the K36 SDM.

6.3. Ignition ON.

6.4. Test for less than 1 V between the signal circuit and ground.

6.1. Disconnect the harness connector at the K36 SDM.

6.2. Test for infinite resistance between the seat belt switch signal circuit terminal 4 and ground.

6.3. Test for less than 2 Ω in each control circuit end to end.

7. Replace the P14 passenger air bag disable indicator.


Component Testing


1. Ignition OFF.

2. Disconnect the harness connector at the appropriate B88 passenger seat belt switch.

3. B88 seat belt buckle in the open position.

4. Test for infinite resistance between the signal circuit terminal A and the ground terminal B at the B88 passenger seat belt switch.

5. Replace the B88 passenger seat belt switch.

6. B88 seat belt switch in the closed position.

7. Test for less than 2 Ω between the signal circuit terminal A and the ground terminal B at the B88 passenger seat belt switch.

8. Replace the B88 passenger seat belt switch.

9. All OK.


Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.


Inflatable Restraint Instrument Panel Module Indicator Replacement

Inflatable Restraint Front Passenger Presence Sensor Replacement

Front Seat Belt Buckle Replacement

Control Module References for SDM replacement, setup, and programming