Driver Seat Rear Vertical Motor Stall
The B1664 code indicates that the driver seat control module has detected a stall or stop in the rear vertical adjustment motor, which controls the up/down movement of the rear portion of the seat. The system monitors motor current and position feedback; if excessive current draw occurs without position change, or if the motor fails to respond within a set time, this manufacturer-specific fault is logged for Toyota/Lexus vehicles.
1. Commonly Affected Makes
2. Most Common Causes
- Seized or worn rear seat adjustment motor
- Physical obstruction in the seat track or gear mechanism
- Damaged wiring or loose connection in the motor harness
- Faulty seat position sensor (potentiometer or Hall effect sensor)
- Internal failure of the seat control module (ECU)
- Excessive mechanical resistance causing overload
3. Symptoms You Will Notice
- Rear portion of driver seat does not move up or down
- Seat moves only partially or with jerky motion
- Seat adjustment stops mid-travel
- Clicking or grinding noise from seat mechanism
4. Step-by-Step Diagnosis
Check for physical obstructions under the seat and in the track mechanism
Inspect wiring and connectors to the rear vertical motor for damage or corrosion
Test motor operation by applying direct power and ground; if no movement, replace motor
Measure motor current draw during operation; compare to specifications
Verify position sensor feedback with a scan tool or multimeter
If all else passes, replace or reprogram the seat control module
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, it is generally safe to drive, but the rear seat adjustment will be inoperative. Avoid adjusting the seat if it is stuck to prevent further damage.
How much does it cost to fix?▼
Repair costs typically range from $150 to $600, depending on whether the motor, wiring, or control module needs replacement. Labor adds $100–$200.