B1729
Seat Driver Rear Down Switch Circuit Failure
Body Chassis/Safety Seat Control System 🟢 Low — Fix at next service
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What This Actually Means
In plain language — no jargon

The rear driver seat down switch isn't sending the proper signal to the vehicle's control module, similar to a light switch that's broken and can't tell if the circuit is on or off. This prevents the seat from being lowered or the system from recognizing the seat position.

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Symptoms You May Notice
3 known symptoms for this code
Rear driver seat down button does not function
Seat position indicator displays incorrectly or continuously
Warning light illuminated on dashboard
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Embedded Systems Insight
What the ECU/ECM is actually computing

The ECU monitors voltage signals from the rear driver seat down switch circuit to detect button activation. It expects a voltage transition when the switch is pressed and released, typically between ground (0V) and battery voltage (12V). A fault is triggered when the ECU detects no signal change, an open circuit, or a short to ground.

Voltage & Parameter Thresholds

Parameter Normal Range Fault Condition
Switch Signal Voltage 0V to 12V transition on activation No transition or stuck at single voltage
Circuit Resistance < 5 ohms when activated > 100 ohms or open circuit
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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 connector at the seat motor control module for corrosion or loose pins.
2
Seat down switch
Test switch continuity with a multimeter; replace if no continuity detected when pressed.
3
Wiring and relay
Check for damaged wires or corroded relay contacts in the seat control circuit using a wiring diagram.