What does it mean?
B1740 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Driver Seat Front Down Switch Circuit Malfunction .
Symptoms
- Front of the seat cushion will not lower, or drops in short jerks
- The remaining seat adjustments still work normally
- Seat starts to move and then stops before the switch is released
- Memory positions cannot be recalled because one axis never completes
- Code returns after clearing, often only once the seat has been operated
Likely causes
- Contaminated or worn contact on the front-down side of the height rocker
- Dried spill inside the switch pack leaving a conductive film across the contacts
- Chafed or broken front-down signal wire where the loom bends at the seat rail
- Corroded, loose or backed-out terminal in the under-seat connector
- Front height motor with a shorted winding or a seized gearbox loading the circuit
- Seat or memory module input stage failure
How to fix it
- Read codes and watch the front-down switch input live while pressing and releasing the rocker
- Remove and inspect the switch pack, cleaning contamination from the contacts
- Substitute a known good switch pack if available to confirm or clear the switch
- Check continuity and resistance of the front-down wire between switch, connector and module
- Wiggle the loom along the rail and under the cushion while monitoring for signal dropout
- Measure the current draw of the front height motor and check the mechanism moves freely
- Repair wiring or replace switch, motor or module according to what the tests show