Just got this 96 S320, and it has a few minor issues. The button on the dash doesn't make the read head restraints fold down or even release. Is there a manual override? Best bet for repair?

 

Does the button show only one graphic? If so, the headrests are "retract only" style, and that is handled by the PSE (Pneumatic System pump) pump under the passenger rear seat.

See the first attached thumbnail for what I'm talking about with the graphic question.

If your button looks like that one (ignore the dot, mine doesn't have, nor have I ever seen one with a LED indicator), then push and hold the button and listen for the pump to run. The ignition key must be in #1 or #2 position.

If you don't hear the pump run, try pulling the fuses for the pump (I think #5 & #12 in the trunk fuse box) for about 5 minutes, and try again. If you still don't hear the pump run, then something's wrong with the pump or the wiring from the button to the pump.

If your door locks still work, then the pump is probably fine.

If you hear the pump run, then maybe the hoses have come detatched at the pump or at the seat back, or the pods on the releases are shot.

Getting at the pump is easy - two red levers at the bottom of the rear seat near the footwells. Push lever (or pull - I don't remember which) and lift on the seat. It slides forward and out.

There are 3 attachment bolts for the seat back along the bottom - 10mm socket.
There are 2 attachment bolts for the seat back along the sides at the top. Pull the door seal loose at the back of the door frame (the cloth covering) and then remove the wiring chase cover at the seat edge - it just snaps loose. You'll see the 2 bolts at the top of the channel.
There are 2 more bolts in the middle of the seat just in front of the first-aid kit box. You have to get the box out first - I think there are 4 or 6 very small phillips screws that hold it in to the hat shelf, plus another inside the box itself. I think you can slide it out without removing the speaker grilles.
Remove the last 2 bolts and the seatback should be free.

CAUTION - it weighs a LOT more than the seat bottom - you'll need a helper to keep from tearing stuff up. The brackets and braces on the seat back are SHARP - wear gloves or take care.

Tilt the top of the seat back forward about 6 inches. You should see 2 plastic hoses going to each of the headrests. If they're attached, use a 7mm open-end wrench between the hose end and the connector it attaches to to gently pop it loose. I'm pretty sure the seat releases are vaccuum operated.

Use a mity-vac to test the vaccuum pods.

The PSE pump will also store trouble codes for its various consumers. I don't know how diagnosable the system is on a '96 - on a '92 it's a piece of cake, because the systems in the car are still analog. I don't know about a '96, might be all digital.

If your button looks different - see the 2nd attachment - then you have power headrests, which only come (far as I know) with power rear seats. You'll know if you have power rear seats, as there will be seat control switches on each of the rear doors. If they're not working, the diagnosis/repair is far more complicated. I can assist there too, if required.

When reinstalling the rear seat, make sure the headrests are in their upright position, and take care to not tear up the hat shelf with the center mounting bracket. Make sure the hat shelf tucks neatly into place where it should before reattaching the bolts. I've had the best luck with starting with the upper 2 bolts and then working from there.

Good luck - let me know if you have any further questions.

 

Wow! Thanks! Guess what I'm up to this weekend!
My S320 just has the down only button. I'm hoping for fuses, but we'll see. I was under the back seat last week cleaning out the residue of the car's past lives, so at least this time it will be a clean operation.