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'96 seat side bolsters



Anyone happen to know anything about the side bolsters in the '96 seats? My driver's side left bolster barely moves at all, seems to be stuck in the full "wide" position. The right side moves in completely, however doesn't stay there once the button is released. The passengers side of the car works fine. Am I looking at replacing a motor, or seat back internals? :hb

HI there,
You have a air operated pump, with air bladders in the sides, as well as the back.
Now, you most likely have a air bladder that is leaking. The reason why your other side goes down, is that the bladder is leaking the air to the other side.
You will have to remove the cover to replace these air bladders.
Besttoyou, c4c5:hb
c4c5...have you seen my question regarding the use of bosch/ford racing injectors in my 95 vette LT1? Am told that they are totally compatible...would save considerable dinero over OEM and any after markets I've seen. Is it true that they'll work?

-You have a air operated pump, with air bladders in the sides, as well as the back. -

I knew the earlier C4s had the airbladders, didn't realize the new style seats in the later C4s ('94?-'96) still used air bladders. The right side bolster in the driver's seat doesn't "relax" (for lack of a better term) all the way out after setting it...it just won't stay in the completely closed position (I like a tight fitting seat). The left side moves only slightly in and out.

The lumbar support doesn't appear to use air bladders either. The fore and aft movements of the 3 lumbar locations all sound to be electric motors and it feels like a rod of some sort in the seat. I've sat in the earlier C4 seats (a '93) with the air bladders and my seats don't feel or sound anything like those. I'll see if I can pull the seat apart a little bit and find out for sure what it uses for supprt. Thanks

Hi LT1vettepilot,
The 1993 Sports Seats had 3 air bladders for the lunbar support only, with 3 air release valves to adjust the bladder pressures after bneing inflated. The side bolsters were mechanical, using electric motors to move the bolsters in and out.
The lumbar supports were inflated with a small diaphram type air pump located under the seat cushion. The diaphram, (made of thin silicone) had a tendancy to tear around the actuating rod that moved the diaphram. A kit was offered from Chevy for X$$$ I don't remember the price, but was fairly expensive. I made two new diaphrams for mine that lasted for years, were still working when I traded the car in on my 2002 Z06. These are the very seats you referanced sitting in. How long have you been experiencing the side bolster problems? Try checking the switch and wiring to the side bolsters, if they are electrical. I'm sure I read someplace a long time ago that the air bladders were changed to electric servos when the seat supplier changed in 1994.
Vettepilot (Dad)
RE: vettepilot

I believe when bought the car, the side bolsters were worn...I didn't happen to notice it until the other day when I was cleaning the seats and had "opened" the bolsters up to get into the creases and then "closed" them again. The outboard bolster didn't move as much as the inboard. I checked the passenger seat again this afternoon and it seems to do the same thing. The outboard bolster on the passenger seat didn't move as much as the inboard. However the passenger's inboard stays where it is put, even when completely closed. I think perhaps the outboard bolsters may have been designed this way, I'm not really sure now.
You could be correct about the design of the outside bolster v.s. the inside, cause the outside bolster has to contend with the support provided to the driver by the doors (outside portion of the seat), could be the design engineers took into consideration the lateral support provided by the doors and designed the outside bilsters accordingly. ????
Maybe somebody with a 94 thru 96 can provide some insight on this???
H ithere,
Sorry, misread here.
Long days.
Anyway, the lumbar is air blader control.
The side bolsters are operated off a motor, and gear assembly, located in the lower seat back.
What you are describing, it is very strange.
Do you hear any ratcheting sounds??
Do you hear the motor running??
I have seen a few that have been broken underneath, at the seat frame, due to use.
You would still have to remove the seat cushion.
Please let us know, c4c5:hb
-crc5 specialist-

<Do you hear any ratcheting sounds??>
Nope...nothing sounds like stripped gears. Sounds fine

<Do you hear the motor running?? >
Yes....until the inboard bolster reaches full closed then the motor stops. When the button is released, the bolster starts to slowly open back up like the motor is slipping, but no odd sounds when it does.

<I have seen a few that have been broken underneath, at the seat frame, due to use.
You would still have to remove the seat >

Ok, I'll pull the bottom cushion out and see if I can find anything broken. I haven't figured out how to pull the top apart yet except for the ziper in the back for the cover, but haven't been able to get to the tongue on the zipper.
Where is the pump located for the lumbar? It doesn't sound like the compressors that were in the '93?
HI there,
I usually remove the seat to do a back repair. As for the pump, and relays, these are located under the passenger side seat.
Let us know what you have, c4c5:hb
Ok, here is what I've found.
Both of the seats run off of one small air pump (about the size of a fish tank air pump) underneath the passenger's seat cushion mounted to the seat frame. It has one air line going out to a distribution control box on left side of the passenger seat frame. From that control box, there are two hoses going into the seat back, and two hoses that go over to the driver's seat. Plus all the associated wiring for the box and pump. The lumbar and seat bolsters are both air operated bladders. I cannot hear any leaking from the pump, lines, or seat bladders after filling them fully. So here is my predicament. I don't want to buy all new bladders if I don't have to. This is my primary (read ONLY) mode of transportation to and from work so I can't spend a whole bunch of time trouble shooting the problem. I think it would be safe to assume that the bladders that aren't maintaining air are leaking (probably into the foam and leather hence the reason I can't hear a leak) and the side bolsters that aren't moving much/at all may have a partial blockage of the lines, perhaps the lines are pinched, or they have a very large leak. The latter being the most likely because both bolsters that aren't moving much at all are the outboard ones (closest to the doors) and would probably have the most stress wear on them from entry and exit of the driver/passenger. So here is my next question...How difficult is it to remove/replace the side bolster bladders and lines in the seat back? And...How much is this going to cost me?(anyone done this before?) I don't see any problems in doing the work myself...I am after all an aircraft mechanic...I think I can figure out a Corvette. Though I must admit, Vettes seem to be a bit more technologically advanced :D

Just thought about what you were describing about the air lines.
I wish I had the seat controls in front of me but since I don't and you do, what about the seat control itself. Does each seat have a lumbar control, or are they individually controlled from the same control panel on the center console? My train of thought here is if both seats are acting the same, there must be a common point where the two control systems come together, The only place that could be is down stream from the pump, and upstream from the bladder, what lies between those two, the control head maybe? Just a thought because as you know I'm not familiar with that year Vette.
Might be nothing more than a leaking valve, partially stuck valve from dirt or something.
The only place where both seats are connected is at the control box. There is one line going into the rear (long edge) of the box from the pump and four lines coming out of the side of the box (2 to the passenger's seat, 2 to the driver's).
Both seats are controlled by a single set of controls in the center console. One pad for seat movement (forward, backward, up, down, tilt front/back) and one pad for lumbar and side bolsters. (3 duel purpose buttons for lumbar-inflate/deflate, and 1 duel purpose button for the side bolsters-inflate/deflate). A single slide switch selects which seat is being controlled.

See picture
I would try to isolate the two lines going from the control head to the passenger seat first. Since that seat isn't need to drive everyday, you could work on that one until you figure out which line controls the side bolsters. Then see if you can get that one working. by the time you finish with that one, you will have a very good idea of what to look for in the driver's side, and probably be able to get that one fixed (barring needing parts) in no time at all. That way the car isn't tied up in an "non-driving" state for more than a couple of hours. Plus, if you find that the only way to fix the side bolsters is to replace the bladders, you can get the parts on order ASAP.
I might have some spare time today and I'll see if I can locate the problem in the passenger's seat. There isn't too much of a big rush on getting them fixed right now, but I do want to get it done before to long as I don't want it to get worse and perhaps damage anything else. Plus the cold weather may play havic with the system as well if plastic or rubber parts are already worn. They may become brittle and burst. I'll keep the forum updated in case someone else comes across the same problem.:(

I will be interested to hear what you learn. I have a 94 with the same style seats. However, my problem is that nothing moves - lumbar, back, shoulders, bolster. I can hear the relay clicking and it feels like something bumps, but that is all I get in either seat.

Question: How do you get the seat bottoms out?

Thanks and Good Luck.

I'll keep this updated and let you know what I discover.
To get the seat bottoms out, look underneath the front of the seat, in the center there is a piece of plastic that looks like a couple of buck teeth with a thin metal bar going across the base of them. Pull that thin metal bar down and push back. That bar is a loop attached to the seat bottom. Once you pop that off the seat bottom will pull right up. Installation is in reverse of removal. Its kind of tricky to get the loop back down around the wiring and to snap it back over the teeth. Not too difficult though
Latest news

Ok, I have both seat bottoms out of the car, I still haven't been able to get the seat backs apart so I can't check the bladders. I made an error in a previous post about the hoses coming out of the control box. There are 5 lines coming out of the control box that go into the passenger's seat. There is one red, one white, one blue, and 2 black. I assume the colored ones go to the lumbar, and the two black ones go to the side bolsters, i.e. one for each side. There is a "T" fitting in the hose coming from the pump to the control box (which I belive is actually a valve body now). The "T" fitting has one line going into the valve body and one line going to a SECOND valve body under the driver's seat which I somehow missed last time I had the seat apart. Thats what I get for working in the dark:cool
Each hose is held in place by some sort of sticky substance. Not really a glue as it can be wiped off, almost like a semi-clear grease, but its not lubricating, just tacky. The main line coming out from the pump aparently needs some more of this mistery tacky stuff as it slips off when I run the side bolsters. The air pressure is to great. Holding the hose firmly in place doesn't alleviate the deflating bladders though. With the seat cushion in place, the hose doesn't seem to come off. I belive the hose bend is up against the cushion and therefore is held in place against the air pressure. I tried to use a tie strap to hold the hose onto the outlet tube, but that didn't help. As a matter of fact it pulled the hose off of the tube because the tube is cone shaped. So I am back to still having no answer to the problem. It could be that both valve bodies have gone bad and aren't sealing completely. If that were the case, I would expect to hear an airleak from the bodies, which I don't. So it still leads me to believe I have leaking bladders in the seat (you may refrain from the "bladder control" jokes, thanks.:J )
So until I can get the seat covers off of the seat backs, I'm stuck. Anyone have any idea how to do this? Without the use of sharp objects used in a cutting motion across the leather of course.
There is a zipper on the back of the seat, however I can't seem to find an end to it. At the top of the seat, it is sewn together, at the bottom it is folded into the seat and I can't find a pull tab. I'll keep trying to get my hand between the seat cover and seat back and see if I can find a pull tab. Thats really the only place there could be one.
Have you used a soapy water solution to check for leaks around the fittings and where the hose attaches to all other parts? If you have enough hose to the pump, and/or other loose connections, try cutting the small amount that normally slides onto the
fitting(s). The new section that hasn't been expanded yet might make a better seal, and maybe hold tighter.
To find the zipper end, try probing carefully in the end with somthing that won't tear, cut, or otherwise scar the vinyl seat back material. Something made of nylon or some other non-metallic tool.
No, I haven't tried that. There is alot of electrical stuff in the area and not really any room underneath everthing to place something to catch the water.
The connection at the pump is a right angle connector that splices the straight tube onto the pump tube. Can't really cut that to make a tighter fit.
I seem to have found the end of the zipper up inside the seat...doesn't feel like there is a pull tab on it. I'm also working in a confined space in the garage with the seat still in the car since its been really nasty outside lately. I'll probably end up waiting until we get some decent weather again and take the seat out of the car. I'll probably have better luck working on it that way.

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