B1729

Code

Other B — Body

Seat Driver Rear Down Switch Circuit Failure

Brand: Other

Type: B — Body

Views: UK: 25 EN: 44 RU: 19

AI status

Completed

ready

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Page language: EN

Causes

Broken or chafed wiring in the seat switch harness
Corroded, loose or contaminated connector at the switch or seat control module
Failed driver rear down switch (mechanical or internal electrical failure)
Blown fuse or lost power/ground to the seat circuit
Faulty seat control module (rare)
Intermittent fault from seat movement or broken solder/joints in switch assembly

Symptoms

Driver seat rear-down (rear-lower) function does not respond or works intermittently
Seat moves one direction only or stops mid-travel
Diagnostic trouble code B1729 stored and may reappear after clearing
Possible other seat-related codes or seat behavior anomalies

What to check

Read and record DTCs and freeze frame with a scan tool; note conditions when code set
Visually inspect switch, switch bezel, and surrounding trim for damage, contamination or foreign objects
Inspect wiring harness under the seat for chafing, pinches, or broken wires — pay attention to harness routing through seat frame pivot points
Check connectors at the switch and seat control module for corrosion, bent pins, or loose terminals
Verify related fuses and power distribution for the seat circuit
Attempt to operate the seat while observing connectors (carefully) to reproduce fault or intermittency

Signal parameters

Switch is typically a simple open/closed contact: when closed it should show continuity (very low ohms) across the switch terminals
With key on, expect either near-battery voltage (~12 V) on the switch feed or a logic level (some modules use a pulled-up signal; readout may be 5 V) — voltage should change when the switch is actuated
Expected continuity when actuator pressed; expected open when released (or vice versa depending on switch design)
Intermittent or fluctuating voltage indicates broken conductor, poor contact, or intermittent switch

Diagnostic algorithm

Retrieve and record all seat-related DTCs and freeze-frame data. Confirm B1729 is current or stored and note conditions (ignition on, seat movement).
Perform visual inspection: remove necessary trim to access the driver rear down switch and wiring. Look for physical damage, corrosion, or trapped debris. Ensure connectors are fully seated.
Check fuses and power/ground to the seat control circuits. Replace any blown fuses and re-test.
With ignition ON and seat power enabled, back-probe the switch connector. Measure reference feed voltage and ground with a digital multimeter. Compare to expected values (see Signal Params).
Operate the rear-down switch while watching voltage or continuity. Confirm the signal changes reliably with each actuation. If signal does not change, the switch or wiring is faulty.
If intermittent, perform a wiggle test: move the harness and seat through full travel while observing the signal. Intermittent changes point to broken wires at pivot points or poor connector contact.
If no power at the switch, trace back to fuse, relay, or the seat control module input. Repair open or short circuits as found.
If switch tests good (continuity and voltage change) and wiring is intact, check the seat control module input with a scan tool or scope to confirm it is receiving the correct signal. If the module input is not registering a valid signal despite a good switch, suspect control module fault or internal wiring issue.
Repair or replace the faulty component(s): repair wiring or connectors, replace the switch assembly, or replace the seat control module only if diagnostics isolate it as the failure.
Clear codes, re-check, and perform full functional test of seat operations and road test if required to confirm repair. Re-scan after test drive to ensure no recurrence.

Likely causes

Damaged harness or connector at the seat (most common)
Failed switch contacts (wear or contamination)
Loose/poor ground or missing power feed to the switch
Connector corrosion or bent pins causing open/short
Faulty seat control module (least likely)

Fault status

⚠️ Status

The seat driver rear down switch circuit is reporting abnormal behavior (open, short, or intermittent). The seat control module has logged a fault related to the driver rear-down input.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours