What does it mean?
If you discover that your OBD II equipped vehicle has stored a code B1660, it means that the body control module (BCM) has detected a malfunction in the electrical circuit that supplies voltage to the motor that makes the driver seat move upward in the front. In some models this may be referred to as the front tilt function. The key components of the electronically adjustable seat are the switch, the motors, and the BCM. The switch is the part with which most drivers are most familiar.
It is what you touch when you want the seat to change positions. It is also the part that is most likely to be broken or damaged by liquids like soft drinks and coffee. If the vehicle upon which you are working shows signs that liquids have been spilled into the power seat switch, you may save yourself some time by replacing it now (the switch – not the vehicle). Power seat switches are normally of a multiple contact variety.
This design makes it possible for multiple functions to be controlled using a single switch. The switch typically has a constant supply of battery voltage applied to it via a fused circuit. When the appropriate button on the switch is pushed or rocked, contacts inside the switch are closed; allowing a particular circuit to be energized and a particular function initiated using a powerful electric motor (or motors). An assortment of strong electric motors is at the heart of the power seat.
They are typically mounted to the seat frame and assisted by small transmissions and steel cables. When battery voltage (and ground) is introduced to the electric motor, it slowly turns and torques a steel cable and the respective transmission. Gears on the motor and the transmission are arranged so that they can actuate the desired movement of the seat frame. If the motors are the heart of the system, the BCM is the brain.
It monitors and controls voltage to and from the switch and the motors, as well as seat position. Many of today’s vehicles also use power seat memory. In this case, the BCM is responsible for storage of individual memory settings and their application at the appropriate time and under the correct circumstances. The BCM is also responsible for monitoring and controlling hundreds (possibly thousands, depending upon make and model) of other functions.
If the seat fails to move when the power seat switch is actuated, a code B1660 will be stored.
Symptoms
- The front of the driver seat cushion will not lift when the switch is operated, while other seat movements may still work
- No sound at all from the motor when the front up function is selected, which points to an open circuit rather than a jammed mechanism
- Memory seat recall does not complete and the seat stops part way through
- The function works intermittently, often returning after the seat is moved fore and aft
- Driving position cannot be set correctly, which affects comfort and visibility
Likely causes
- Liquid spilled into the power seat switch, which corrodes the internal contacts and is one of the most frequent causes
- Open circuit in the seat harness where it flexes under the seat as the seat slides on its rails
- Connector under the seat pulled apart, dirty or with a pushed out terminal, often after floor cleaning or seat removal
- Burned out or open winding in the front lift motor of the driver seat
- Blown fuse or open feed to the power seat circuit
- Corroded seat ground point on the floor pan
- Failed output driver or lost configuration in the body control module or the seat module
How to fix it
- Check the seat fuse first and confirm battery voltage reaches the seat switch
- Look for signs of spilled drinks around the switch and in the connector, since a contaminated switch is a very common cause
- Operate the switch and measure whether voltage and ground actually appear at the motor connector, since the motor needs both to turn
- If the voltage reaches the motor and nothing happens, apply a controlled supply directly to the motor to prove whether it is open internally
- Inspect the harness under the seat where it bends with the rails, and check the connector terminals for corrosion or push out
- Clean and tighten the seat ground point and repair any damaged wiring section
- Replace the switch or the motor according to the measurements, and treat the control module as the last option, remembering that memory functions may need to be relearned afterwards