Driver Seat Rearward Switch Circuit Failure
B1721 is a manufacturer-specific diagnostic trouble code indicating a fault in the driver seat rearward movement switch circuit. The seat control module or body control module has detected an abnormal electrical condition in the signal from the rearward position switch, such as a short to ground, short to voltage, open circuit, or resistance outside calibrated thresholds. This affects only the comfort function of the driver seat's rearward longitudinal adjustment.
1. Commonly Affected Makes
2. Most Common Causes
- Faulty driver seat adjustment switch with damaged internal contacts
- Wiring shorted to ground, shorted to voltage, or open between the switch and seat control module
- Corroded, bent, or loose pins in the switch or seat module connector
- Excessive circuit resistance due to oxidized splices or terminals
- Internal failure of the driver seat module (DSM) that processes the switch signal
3. Symptoms You Will Notice
- Driver seat does not move rearward when the switch is activated
- Seat may move in other directions but not rearward
4. Step-by-Step Diagnosis
Check for other related DTCs and verify the symptom
Inspect the driver seat switch and its wiring for visible damage or corrosion
Test the switch continuity and resistance per manufacturer specifications
Check for shorts to ground or voltage in the signal circuit
If wiring and switch are good, test the seat control module output and consider replacement
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, it is safe to drive. This code only affects the rearward seat adjustment comfort feature and does not impact vehicle safety or drivability.
How much does it cost to fix?▼
Repair costs typically range from $100 to $400, depending on whether the switch, wiring, or seat module needs replacement and the labor rates in your area.