Driver's seat adjustment problem

Colin M · October 24, 2016

Hi guys

I hope someone will be able to help me with a backward and forward seat adjustment problem that I have just encountered.

I went to move the seat forward to my normal driving position and instead of the usual smooth adjustment there was some juddering. This did not improve as I tried to move the seat backwards and forwards, and then the seat movement stopped altogether. It would not adjust backwards or forwards when pressing the switch and the seat seemed slightly offset, with the side nearest the door a bit further forward than the side nearest the transmission tunnel. I have unbolted the seat from the floor to have a look underneath to see what the problem is. When pressing the switch the runner on the door side moves properly (what looks like a threaded rod spins round and moves the runner backwards or forwards) but there is no movement at all from the threaded rod on the other side and the runner stays where it is. Presumably this is why, when the seat is bolted to the floor, there is no movement at all either backwards or forwards when pressing the switch - one rod is not moving at all, so the seat stays where it is.

It occurs to me that a wiring fault may be preventing the runner from moving. Does anyone have a wiring diagram which could identify the relevant wire which provides the power to the non-moving runner? If anyone knows how to remove the backwards and forwards adjustment switch and the plastic trim on the door side of the seat, that would also be helpful.

Any help, suggestions or ideas gratefully received!!

Many thanks.

runsgrateasanut · October 25, 2016

Could this be the common problem Colin? Not sure if you are getting no movement fwd/back

http://www.clublexus.com/forums/ls-1st-and-2nd-gen-1990-2000/442318-how-to-fix-the-problem-with-non-working-reclining-on-drivers-seat-pictures-inside.html

see thread Driver seat 1992 Lexus for comments

Fixed mine whilst Car seat was still in situ.

Colin M · October 25, 2016

Thanks for this, Stuart, which was an interesting read, but unfortunately I do not think it helps with the problem I have.

The problem is not with raising/lowering the front and back of the seat, which works ok when the switch is pushed up and down at each end, but with getting forwards and backwards movement. If I get a problem with raising/lowering (hopefully not!), the thread will be very helpful and I have made a note of it for future reference if needed.

I have made some progress towards getting the seat back into a position where I can drive the car. In its current position (fully retracted), I would need to grow at least a foot in height in order to reach the pedals! I have found that the threaded rod on the transmission tunnel side that does not spin round when the switch is operated can be moved manually by turning the nut on the end of the rod at the front of the seat (which is visible if you remove the two screws holding the black plastic trim at the bottom of the front section of the seat that is facing the brake/accelerator pedals). As the seat is fully retracted at present, the nut unfortunately has to be turned anti-clockwise in order to move the seat forwards. Yes, this means that nut unscrews from the rod rather than turning the rod! So I have put some loctite on the nut in the hope that when I try it again the rod will turn and the nut will not unscrew. Fingers crossed!

Perhaps the long term solution is to see if I can locate a replacement seat on which all the electrics work. Then unbolt the seat from the electrical undercarriage and bolt my seat onto it. Has anyone got a driver's seat with working electrics that they would be willing to sell me?

ambermarine · October 26, 2016

Colin

Take the seat out of the car and it will be easier to identify the cause of the problem there are several motors in the seat and they are easy to replace after identifying which one is faulty.

This is easier and less costly than replacing the whole seat which you will need to remove to fit a replacement.

There are four fastenings two at the rear under the plastic covers and likewise at the front.

Colin M · October 27, 2016

Thanks, Phil. I have removed the seat to have a look.

As far as I can tell, there is not a faulty motor. The motor that moves the seat backwards and forwards works when I move the switch backwards and forwards but it only operates one seat runner. The two runners are connected by a rod running between them which joins them together, so it seems unlikely that there will be a separate motor for each seat runner. If this is the case, the fault might lie with the non-operating seat runner mechanism - this might explain the juddering that occurred and the lack of smooth movement when I first tried to move the seat.

However, the good news is that I have managed to turn the nut to move the threaded rod so that the seat has moved forward on the runner. The loctite held for a while and then failed but there is just enough thread visible to put a second nut on to act as a lock nut to prevent the nut from unscrewing. By gently turning the nut with the lock nut in place to move the runner forward and operating the switch to move the other runner forward a bit at a time so as to keep the seat level on the runners, I was able to get the seat into the position where I have it for driving.

steve2006 · October 27, 2016

Colin, have a good look for foreign objects in the seat runner, the one nearest the transmission tunnel often gets coins or other bits dropped down there which could jam the mechanism.

I will also send you the exploded diagram of the seat base.

ambermarine · October 27, 2016

Hi Colin

I have to concur with Steve it sounds like a foreign object as fallen into the worm gear on the runner drives ,this may not be apparent at first inspection and you may have to dismantle the worm drives .

Colin M · October 27, 2016

Thanks, guys, that's very helpful. Something stopping the worm gear on the runner does seem to be the most likely explanation and I will investigate this further sometime next week (no time before then).

It would still be helpful to have the exploded diagram of the seat, Steve, so I can see how things are put together.

Thanks a lot.

Hopefully I will be able to get it sorted.

steve2006 · October 27, 2016

6 hours ago, Colin M said:

Thanks, guys, that's very helpful. Something stopping the worm gear on the runner does seem to be the most likely explanation and I will investigate this further sometime next week (no time before then).

It would still be helpful to have the exploded diagram of the seat, Steve, so I can see how things are put together.

Thanks a lot.

Hopefully I will be able to get it sorted.

You should already have it in your profile section, if not let me know and I will send as a PM.