OBD Code B1699: Passenger's Seat Occupied Switch Circuit Short to Ground

Q: What does OBD code B1699 mean?

Passenger's Seat Occupied Switch Circuit Short to Ground. The passenger seat occupancy sensor is sending a constant ground signal to the ECU, like a light switch stuck in the 'on' position. This prevents the system from detecting whether someone is actually sitting in that seat.

Q: What are the symptoms of fault code B1699?

Passenger airbag disabled warning light illuminates, Airbag system malfunction indicator on dashboard, Passenger-side airbag may not deploy in collision

Q: How do I fix OBD fault code B1699?

Inspect and reseat the passenger seat occupancy switch connector for corrosion or loose pins.. Check the circuit wiring for damage, pinching, or exposed conductors creating an unintended ground path.. Replace the switch assembly if connector and wiring are intact.

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What This Actually Means

In plain language — no jargon

The passenger seat occupancy sensor is sending a constant ground signal to the ECU, like a light switch stuck in the 'on' position. This prevents the system from detecting whether someone is actually sitting in that seat.

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Symptoms You May Notice

3 known symptoms for this code

Passenger airbag disabled warning light illuminates

Airbag system malfunction indicator on dashboard

Passenger-side airbag may not deploy in collision

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Embedded Systems Insight

What the ECU/ECM is actually computing

The ECU monitors voltage on the passenger seat occupancy switch circuit. It expects a high voltage signal when the seat is empty and low voltage when occupied. A short to ground keeps the signal abnormally low regardless of seat status.

Voltage & Parameter Thresholds

Parameter	Normal Range	Fault Condition
Occupancy Switch Voltage	5V when empty, 0.5V when occupied	Constant <0.2V (short to ground)
Signal Response Time	Voltage changes within 100ms of weight change	No voltage transition detected

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Diagnostic & DIY Fix Guide

Check these in order — from cheapest to most complex

1

Wiring harness connector

Inspect and reseat the passenger seat occupancy switch connector for corrosion or loose pins.

2

Wiring harness

Check the circuit wiring for damage, pinching, or exposed conductors creating an unintended ground path.

3

Passenger seat occupancy switch

Replace the switch assembly if connector and wiring are intact.