I have recently attempted to install an aftermarket stereo in my 90 Rx7 convertible. I bought a stock harness adapter & mounting kit. I got the front speakers to come on, but that's it. There are a couple of missing terminals on the aftermarket harness; probably since it's a convertible. Anyways, I checked the continunity on all the wires from the center console headrest controller etc. with no avail. I've checked the Hayes car manual for wiring diagrams, etc. Nothing there either. So I've checked everything that I can think of. So I'm asking help from anyone who has done this or has knowledge they would like to share with me. Thanks

You have to splice power to the pre-amp, that was unplugged when you took the stock stereo out, to make the headrest speakers function normally.



Or you can run speaker lead from deck power to make just the headrest speakers work, but you lose the volume control in the console, and they get very loud and obnoxious



If the wiring was done correctly the dash and door speakers should function normally now.

What about the door speakers, are those working? I remember when reinstalling the stock radio on my S4 vert (the previous owner had taken it out, installed his own, then took it out before selling the car but left all the messed up wiring for me to deal with), the only ones that worked were the under-dash speakers. If the door speakers arent working, u may need to run leads to the external amp for them (should be located under the dash, drivers side, above the dash speaker)

[quote name='89 Rag' date='Sep 12 2005, 01:41 PM']You have to splice power to the pre-amp, that was unplugged when you took the stock stereo out, to make the headrest speakers function normally.



Or you can run speaker lead from deck power to make just the headrest speakers work, but you lose the volume control in the console, and they get very loud and obnoxious



If the wiring was done correctly the dash and door speakers should function normally now.


[/quote]

Is there a preamp in the headrest control? I cant find any extra amp anywhere in the car. I'm not sure if the rear speakers are connected right now or not and not sure where to send power to. Sorry if I'm not getting it.

[quote name='toplessFC3Sman' date='Sep 12 2005, 05:38 PM']What about the door speakers, are those working? I remember when reinstalling the stock radio on my S4 vert (the previous owner had taken it out, installed his own, then took it out before selling the car but left all the messed up wiring for me to deal with), the only ones that worked were the under-dash speakers. If the door speakers arent working, u may need to run leads to the external amp for them (should be located under the dash, drivers side, above the dash speaker)


[/quote]

I don't have dash speakers, only door, behind the seats, and headrests, that are controlled by a center console control. I've looked behind the rear speakers for a preamp and I doubt there's one in the doors.

Pull the cover off of the spare tire compartment, where the top folds into in the down position. In the lower right, behind the driver's seat, next to the seatbelt retractor mechanism, is the pre-amp for the console/headrest controls.



That unit needs to get power, from the new deck you installed, via the wiring that was unplugged from the old unit if you want the headrest speakers to function as they were in the stock config.



You might have to plug the stock unit back in and run a test light to establish which wires are hot when the key is in the on position.

Is this a difference between the S4s and S5s? my 88 doesnt have speakers behind the seats, but does have two under the dash, in addition to the door speakers and headrest speakers.

[quote name='89 Rag' date='Sep 14 2005, 01:29 PM']Pull the cover off of the spare tire compartment, where the top folds into in the down position. In the lower right, behind the driver's seat, next to the seatbelt retractor mechanism, is the pre-amp for the console/headrest controls.



That unit needs to get power, from the new deck you installed, via the wiring that was unplugged from the old unit if you want the headrest speakers to function as they were in the stock config.



You might have to plug the stock unit back in and run a test light to establish which wires are hot when the key is in the on postiton.


[/quote]

Thanks for the help. I really appreciate it. This has been driving me crazy. FYI Someone told me to go to crutchfield.com for a harness and they have specific harnesses which they say will power all the old amps etc., so I ordered one. So if that dosen't work, knowing where the amp is will. Thanks agan.

radio shack and stores like best buy also sell harnesses

OK, the stereo was stolen out of my car a few years ago (89 convertible, 22K miles, in storage). I installed a totally new security system with all the bells and whistles and a new head unit. Well, couldn't get the headrest speakers to work. Turns out the input to the stock head rest amp is not a line level signal, it is a speaker level signal. It was a simple matter once the stereo guy figured it out to run a speaker level signal into the amp. Stock volume controls on console work and everything.