The E-bay advertisement for my car indicated that the power seat switch as broken and had been removed from the vehicle. When the switch arrived with all the spare parts I found that the knob had been broken off and removed. Without the car there wasn't much point trying to do anything with the switch.
18th October 2009: When the car did arrive John made a temporary knob and connected up the switch, which mounts to the left of the instrument panel alongside the electric window switches. Nothing happened when the switch was moved to any of the four positions. John disassembled the switch and cleaned lots of Texan red dust out of it and reassembled it, ensuring that all four positions had their contacts making. He connected it back into the car but when he moved it to the different positions all we could hear was the clicking of the circuit breakers as they heated up and broke the circuit.
Figuring that the seat probably hadn't moved for 20+ years we sprayed as many of the moving parts, bushings and slides as we could access with WD-40. When we next tried to operate the seat it came to life, whirring up, whirring down, whirring forwards and whirring backwards. What excitement ! Peering under the seat it looked a proper mess and so I decided to remove the seat and service it all properly. The Mercury seat is quite nifty in that you can remove the seat base and backrest from the frame by undoing just two bolts and two nuts. You can then tilt the seat into the back seat area and gain access to the works. We did this and found a veritable archeological dig underneath ! We have found some interesting things under car seats in the past but this one takes the trophy. Read more about what we found in the
archaelology page. After gathering up all the historical artefacts we vacuumed up all the dust and red Texas dust and it started to look a bit tidier. I lubricated every pivot point and slide with WD-40 and made sure it was moving freely.
The seat has just one electric motor which drives a double-ended threaded rod via a worm gear. Each end of the threaded rod has a threaded block located on it which engages and disengages with the threaded rod via a clutch which is in turn actuated via an electric solenoid. One end of the threaded rod works the up-down motion and the other end works the fore-aft motion. When the switch is moved, say to the "up" position, the motor begins to turn the threaded rod and the solenoid on the threaded block at one end of the threaded rod engages the clutch and the block begins to move along the threaded rod. This block is connected to the seat frame and pushes the seat up. Moving the switch to the "down" position is the same except the motor is turning in the opposite direction and so the block moves the other way along the rod. Moving the switch to "fore" and "aft" works the same as "up" and "down except the solenoid at the other end of the threaded rod is actuated.
The drive mechanism seemed to be very gummed up and so I decided to remove it to service it properly. It wasn't too difficult. I just needed to detach the moving blocks to seat frame linkages, undo one bolt holding the mechanism to the floor and undo all the wires. Once out of the car I cleaned all the gunk from it with kerosene and then lubricated the threaded rod with a light film of grease. I then reassembled the whole thing and made sure it moved easily and decisively. It now works a treat and I can say it's the first car I have owned with a power seat !
16th January 2010:When the car arrived the power seat switch had been removed because the knob had broken off and become lost. John temporarily fixed it by using a small screw as the knob. Trawling E-bay for seat switches returned a number for the Thunderbird that looked very much like the Mercury switch. I bought one that wasn't too expensive. When it arrived it was nearly identical to the Mercury switch. We connected it up but it didn't work the seat properly. Then we noticed that the wiring connections on the Thunderbird switch were different to those of the Mercury switch. John then set to work pulling the switches apart. He reassembled the front of the Thunderbird switch (with the knob) to the back of the Mercury switch (with the correct wiring connections). We reconnected this to the seat and it worked ! Now we have a working seat switch with a proper knob.
