Volt

Seat Belt Indicator Circuit Malfunction - Rear

The two rear seat belt switches are 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 rear seat belt via serial data to the driver information centre (DIC). After receiving the message, the DIC controls the illumination of the rear seat belt indicators.

1. The mechanical stop in the buckle may prevent latching but the switch in the buckle may momentarily open and the SDM would interpret this as an occupant in the rear seat position and that the buckle was attempting to latch.
2. If a rear occupant attempts to latch the seat belt into the wrong buckle, the indicator may illuminate and the system assumes there is an occupant not buckled in that seat position.
3. An unseated connector can appear as a buckled seat belt connection.

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

Scan Tool Reference

Control Module References for scan tool information

1. Verify that all connectors are fully seated.
2. With a scan tool, monitor the appropriate 2nd Row Seat Belt Status parameter and P16 instrument cluster rear seat belt indicator while buckling and unbuckling the seat belt. The parameter should display Buckled when the rear seat belt is buckled and Unbuckled when the rear seat belt is unbuckled.

⇒	If the scan tool does not display the parameters as specified, refer to Circuit System Testing.

⇒	If the scan tool displays the parameters as specified but the P16 instrument cluster does not display the correct corresponding rear seat belt indicator, replace the P16 instrument cluster.

Note: When removing connectors inspect for damage or corrosion. Damage or corrosion in the following requires repair or replacement of the affected component/connector.

1. Vehicle OFF.
2. Disconnect the harness connector at the appropriate B88 seat belt switch.
3. Test for less than 5 Ω between the low reference circuit terminal 2 and ground.

⇒	If 5 Ω or greater

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.

⇒	If 2 Ω or greater, repair the open/high resistance in the circuit.

⇒	If less than 2 Ω, replace the K36 SDM.

⇓	If less than 5 Ω

4. Vehicle in Service Mode.
5. Verify the scan tool 2nd Row Seat Belt Status parameter displays Buckled.

⇒	If the scan tool 2nd Row Seat Belt Status parameter does not display 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 1 and ground.

⇒	If less than infinite resistance, repair the short to ground on the circuit.

⇒	If less than 2 Ω, replace the K36 SDM.

⇓	If the scan tool 2nd Row 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 2nd Row Seat Belt Status parameter displays Unbuckled.

⇒	If the scan tool 2nd Row Seat Belt Status parameter does not display Unbuckled

7.1.	Disconnect the harness connector at the K36 SDM.

7.2.	Vehicle in Service Mode.

7.3.	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.

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

⇒	If 2 Ω or greater, repair the open/high resistance in the circuit.

⇒	If less than 2 Ω, replace the K36 SDM.

⇓	If the scan tool 2nd Row Seat Belt Status parameter does display Unbuckled

8. Replace the B88 seat belt switch.

1. Vehicle OFF.
2. Disconnect the harness connector at the appropriate B88 seat belt switch.
3. Buckle the B88 seat belt switch.
4. Test for infinite resistance between the signal circuit terminal 1 and the low reference terminal 2 at the B88 seat belt switch.

⇒	If there is not infinite resistance

Replace the B88 seat belt switch.

⇓	If there is infinite resistance

5. Unbuckle the B88 seat belt switch.
6. Test for less than 1 Ω between the signal circuit terminal 1 and the low reference terminal 2 at the B88 seat belt switch.

⇒	If 1 Ω or greater

Replace the B88 seat belt switch.

⇓	If less than 1 Ω

7. All OK.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.