Seat Belt Indicator Circuit Malfunction - Rear
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Seat Belt Indicator Circuit Malfunction - Rear
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Diagnostic Fault Information
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Circuit
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Short to Ground
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High Resistance
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Open
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Short to Voltage
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Signal Performance
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Rear Seat Belt Switch Signal
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1
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2
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2
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2
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-
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Rear Seat Belt Switch Low Reference
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-
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2
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2
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2
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-
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1. Green indicator will illuminate only for the bulb check. The red indicator will remain ON with seat belt buckled.
2. Green indicator will illuminate only for the bulb check. The red indicator will never illuminate.
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Circuit/System Description
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All three 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 center. After receiving the message, the driver information center controls the illumination of the driver seat belt indicator.
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
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1.
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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.
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2.
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If a rear occupant attempts to latch the seat belt into the wrong buckle, the indicatormay illuminate and the system assumes there is an occupant not buckled in that seat position.
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3.
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An unseated connector can appear as a buckled seat belt connection.
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Circuit/System Verification
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1.
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Verify that all connectors are fully seated.
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2.
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With the scan tool monitor the 2nd Row 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.
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3.
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Replace the P9 driver information center.
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Note
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When removing connectors inspect for damage or corrosion. Damage or corrosion in the following requires repair or replacement of the affected component/connector.
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B88 Seat belt switch
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•
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Seat belt switch harness connector
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•
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K36 SDM
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•
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SDM wiring harness connector
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2.
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Disconnect the harness connector at the B88 seat belt switch.
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3.
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Test for less than 5 Ω between the ground circuit terminal B and ground.
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3.1.
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Disconnect the harness connector at the K36 SDM.
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3.2.
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Test for less than 2 Ω in each control circuit end to end.
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5.
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Verify the scan tool 2nd Row Seat Belt Status parameter displays Buckled.
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5.1.
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Disconnect the harness connector at the K36 SDM.
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5.2.
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Test for infinite resistance between the seat belt switch signal circuit terminal A and ground.
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6.
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Install a 3 A fused jumper wire between the circuit terminal A and the ground circuit terminal B.
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7.
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Verify the scan tool 2nd Row Seat Belt Status parameter displays Unbuckled.
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7.1.
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Disconnect the harness connector at the K36 SDM.
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7.3.
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Test for less than 1 V between the signal circuit and ground.
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7.4.
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Test for less than 2 Ω in each circuit end to end.
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8.
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Replace the B88 seat belt switch.
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2.
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Disconnect the harness connector at the B88 seat belt switch.
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3.
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B88 seat belt switch in the open position.
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4.
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Test for infinite resistance between the signal circuit terminal A and the ground terminal B at the B88 seat belt switch.
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5.
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Replace the B88 seat belt switch.
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6.
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B88 seat belt switch in the closed position.
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7.
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Test for less than 1 Ω between the signal circuit terminal A and the ground terminal B at the B88 seat belt switch.
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8.
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Replace the B88 seat belt switch.
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