Drivers Seat Fixed

[Ian Lord]

last year I had a problem with drivers seat back not working I fixed and wanted to share with members

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DRIVERS SEAT - LS 400 (1990) We call it “the Dream Machine”

I wanted to share with members of LOC the answer to a frustrating problem I recently encountered in the hope others can resolve the same problem should it happen on your “dream Machine”

While cleaning the roof with another coat of Car Polish I was standing on the driver’s door sill and inadvertently must have touched recline button on the side of drivers seat leaving the seat in fully reclined position.

When trying to return the seatback to normal driving position the seat twisted, and stopped short of normal, because the LEFT side of the seat was not moving.

I searched both the UK & US LOC forums and found that others had encountered similar problems; in my case I was NOT able to drive the car.

The solution from members was to locate the Aluminium Tube (with black plastic cover) located at the base of seatback this is visible if you look at the junction of seat & seat back near the hinge.

How seat recline works:

The way the recline feature operates is by an electric Motor on right side of seat as you look at windscreen, from this there is a tapered metal spline, and the aluminium tube is ridged inside the tube and slides over the spline by this method the tube connects in the same way to the LEFT side and drives at the same speed as the RIGHT side.

The Problem is:

In my case the LEFT side of the aluminium tube had been cleaned of its ridges (rather like a pencil sharpener) so no drive connection possible to LEFT side of seat.

The solution many LOC members had suggested was GLUE it with Araldite type of glue and let it cure for 12hours or more, I did this twice with ZERO success…

How to Fix:

You will need to remove the seat from the car; there are 4 x 14mm bolts,

•slide seat forward remove 2 rear bolts,

•move seat backwards remove 2 x forward bolts

•You will need lift off carpet covered plastic covers, to find bolts

•Disconnect wiring harness

•Remove seat via rear door

•Remove plastic panel on back seat (2 small Phillips screws at bottom of plastic backing) pull sides of plastic cover off clips on seat frame and slide down to release 2 x clips that go under top of seat frame.

•Free up leather from base of seat back by removing wire loops from wire frame section that attach leather also remove 6 x steel clips (3 each side) so you can release leather and foam filler away from lower seatback frame. (leave seat cushion leather in place)

You can now see the aluminium tube covered in black plastic tube. To release this tube, you need to remove 4 x bolts (2 from each side) of hinge arm that connects to seat back to hinge arms. When removed you will be able to push seat hinges apart just enough to remove the aluminium tube from the steel splines.

NEW ALUMINIUM TUBE:

My friendly local garage called Lexus spares department at main dealer and they faxed over exploded drawing of Drivers seat, (ref: MN 2071-A) the aluminium tube was identified as Lexus part number is: 72501D

My garage called and ordered the part which was available in 3 days at a cost of £11.08 + vat.

I inserted new tube, and put everything back together and all works normally. (Interesting to note that the new part is slightly longer than original which ensures tube does not move from side to side, which is my guess why the problem happened in the first place.

IMPORTANT:

Be sure the seatback is straight (not twisted, be sure both sides of seat are level) when installing the new part, otherwise the seat will twist when electric motor runs, and seat may not return to correct position.

IAN LORD

Membership number: 10742

Location: Bournemouth

[tigran]

Fantastic bit of advice that man! Exactly the problem i'm having with my ls at the moment - meaning the only point at which the seat back is level is in a rather gangster lean pose, which leaves me driving around looking like a Crips member.

Will get on to the guys at lexus Poole asap.

[Ian Lord]

Fantastic bit of advice that man! Exactly the problem i'm having with my ls at the moment - meaning the only point at which the seat back is level is in a rather gangster lean pose, which leaves me driving around looking like a Crips member.

Will get on to the guys at lexus Poole asap.

Hi gangster pose man!!

Sorry to hear you have same drivers seat back problem, and very pleased my post gave you some good news, the seat is very heavy so when taking seat out through the back door, (be sure to place some old towels or carpet on wheeel arch) I did nt and scratched the paintwork!!!!. Before disconnecting the wiring harness (pull apart block under seat) get seat back level (mine was in maximum recline mode) otherwise you will not be able to move it with NO power.

I still have the exploded LEXUS drawing with all the DRIVERS SEAT PARTS (its a fax but I should be able to scan and email to you if this will help?) if you want it send me your email address - My email is: i.lord300@btinternet.com

Good luck

IAN

[TeamDax]

hi.... i did a similar fix a few weeks ago, following a post i found here i did it slightly different

the splines actually go all the way through the inside of the aluminium tube, only the ends wear..... so, i cut the aluminium rod in half (with a hacksaw) cut the worn ends off, re-yatched the 2 bits of aluminium rod and joined them with a section of 15mm copper pipe.... which i drilled and bolted through both sections of aluminium rod. works great.... and you dont need to remove the seat from the car

[runsgrateasanut]

Completed my first long trip in the Lexus after a traumatic experience in getting car back from mechanic with new Cambelt etc only to discover MOT expiry two days later and Ferry booked for third day. Unfortunately, was not so lucky as those who mention pass with no advisories, and in fact it took half a day for Garage to get car through emissions without a fail. I'd had the exhaust pipe gaskets by the Cats replaced at same time of Cam belt change so bit peeved that car should have high CO5 levels even after a burn. Anyway they passed it using half a tank of fuel and possibly doing the Trannie little good, so we made it to the Ferry on the Saturday..

Getting to the point and this particular thread, driving overnight down to the Charente we usually try to have a kip at some point and I realised that I seemed to be facing the window rather more than normal. OK Pillow there so very nice, but the Seat was moving the door side but not the centre side thus twisting me to the window. When upright, still not exactly at right angles to the door so twisting my spine. Now I need to study this thread to understand what to do to correct. If anyone can pm me the exploded seat diagram I'd be grateful. I have to say, that although the overall 1300 mile drive was OK I looked enviously at a White S500 W140 Mercedes sat in the next lane at Calais, as it was in immaculate condition and as a convert to Lexus from the S320 I had a nostalgic moment for the wider seats, not to mention a realisation of the sizeable wad of money I've had to spend to get this car almost to my liking. Further work to be done (Seat/ plugs/leads/ tow bar fit/ lpg tank fit (now dithering) but I suppose I'm getting there. Only other fail point on MOT was Windscreen wipers and Aeros don't fit without a bit of modding. Advisories? Wishbone replacement at some time - more cash out.!! They say you have to be rich to own a Lexus. Or maybe you just buy the right Lexus?

[steve2006]

Good to hear it got through eventually, I'll do you a deal, if you can provide me with some information regarding the high CO level and what was done to get it down I'll provide the seat diagram if you PM your email.

Reason is my other 94 Celsior has failed on CO at 1.1% and I would like to get it sorted before this winter kicks in leaving the car unused and exposed to the elements.

[runsgrateasanut]

Thats a good question Steve and to be honest I don't know to what level, emissions were reduced. At the time I wasn't going to demand a read-out but just grabbed the MOT, paid the bill and ran.

It was Fast idle 0.54 against limit of 0.30 and second fast idle test 0.44 on first fail. I took it for fifty miles drive with injector cleaner before it went back for retesting the following day.

The bill states that they "carried out an exhaust burn emissions - still out of range".

"Carried out extented test drive, emissions still out of range (i know they took the car on a drive and there isnt a good piece of road for speed above 40mph within seven miles.)

"Checked spark plugs and HT leads" (here I am having a difficulty as one side could easily be checked but the other bank requires a bit of work removing air conduit etc. Asked what they looked like - a blank expression was the answer. Wish I'd looked at the plugs when mechanic had parts off to do the cam belt change.

(btw the Cam belt was looking fine but the water pump was beginning a leaking process. All items changed at 113k)

"cleaned all connections and caried our re-test - pass".

So I'm going to need check the plugs - both sides (previous services may have only changed one side???) and check gaps.

Air fliter looks OK to me but needs be checked.

If you haven't put any injector cleaner in your car in recent times then I suggest this is a good idea and give it a burn. Deliver it hot to garage . Otherwise I'm afraid I cant advise. Oh, my mechanic (didn't do MOT) said after fixing the exhaust leaks the car may take time to re calibrate itself for fuel delivery.

Hope this helps?

[steve2006]

Thanks for your comprehensive reply, as a certain supermarket says "every little helps"

Diagram emailed to the address you provided,hope it helps. There was a one time a very good tutorial with pictures for doing the seat repair but as of yet I cannot find it.

Ok after hijacking the thread and going completely off topic I have now resumed it.:)

[runsgrateasanut]

hi.... i did a similar fix a few weeks ago, following a post i found here i did it slightly different

the splines actually go all the way through the inside of the aluminium tube, only the ends wear..... so, i cut the aluminium rod in half (with a hacksaw) cut the worn ends off, re-yatched the 2 bits of aluminium rod and joined them with a section of 15mm copper pipe.... which i drilled and bolted through both sections of aluminium rod. works great.... and you dont need to remove the seat from the car

Did you disconnect the Battery before doing this job? Is it recommended?

[runsgrateasanut]

No reply to my previous Q. re disconnecting Battery before disconnecting various plugs for seat movement.? Anyone?

As I recall the S Class had a thin tensioned cable beneath to do with the seat belt tensioner and I needed to be very careful to disconnect this and not stretch it..

Couldn't see underneath to see if the same exists on the Lexus? (not a long wheel base car)

Also ( feeling a bit stupid here) I can't seem to lift those pieces of carpet to get to the bolts. OK I know i'm the sort of guy who gets sand kicked into his face - weakling etc, Do they pull off?? need levering??

Do hate breaking things.

[runsgrateasanut]

hi.... i did a similar fix a few weeks ago, following a post i found here i did it slightly different

the splines actually go all the way through the inside of the aluminium tube, only the ends wear..... so, i cut the aluminium rod in half (with a hacksaw) cut the worn ends off, re-yatched the 2 bits of aluminium rod and joined them with a section of 15mm copper pipe.... which i drilled and bolted through both sections of aluminium rod. works great.... and you dont need to remove the seat from the car

Just a clarification on this thread, having just removed the tube by only releasing the seat back four bolts with seat in situ, a piece of 15mm copper pipe won't thread onto this tube. 16mm might, but I'm not in france where it is a common measurement. Will need to splice the 15mm to wrap it round. Still a quick fix without removal of seat. Must press on.

RETRACT MY COMMENT - 15mm does fit PERFECTLY., I hadn't champhered the end after it was last cut. Doh!

Edited March 7, 2015 by runsgrateasanut