I have an 87GT with the stock radio and factory "Performance Sound" Subwoofer and amplifier. I was wondering if anyone had ever or knows how I can still use the factory amp and sub with an aftermarket stereo system? Is it even possible? Also I can find replacement aftermarket front 4x10 speakers that fit easily, but according to Crutchfield .com and a few other places I have tried have been unable to locate any good quality 4x6 speakers that will fit in the rear. All of the choices offered other than the no-name ones from the fiero store i have been told are too deep. Any suggestions there? Oh yea, and another thing concerning the subwoofer, I replaced my busted one with a unit from the fiero store, there are 2 wires one being solid red and the other red with a black tracer that connect to the original sub. Does anyone know which is positive and which is negative? Any help would be appreciated.
Jeremy

ok, red is +, red w black is neg.

for the speakers the pioneer 4x10 and 4x6's fit, at least in the 88. seem to recall someone mentioning something about the 84 tho, maybe the pillar is differrent? and I also thought that the 84 had headrest speakers?
for ref, I put these in, they sound great:
Pioneer TSA4103 4"x10" 2-way 120w car speakers
Pioneer TS-G4640R 4"x6" 2-way 100w car speakers

if you used an adapter from the after market head to the original radio harness, the subamp should already be wired.
it uses the combined speaker outputs for it;s source.
here is how it';s wired stock, click it for full size:


now somewhere I had a page explaining how to install an aftermarket unit to it, basically it sums all the speaker lines together internally. the gist of the article was that you use all 4 for full power, but if the new head is much more powerful than the stock unit, you could over load the input, so you would just use 2 of the connections, front right and front left to halve the effective input power so you don;t overdrive the amp.
If I find that page, I'll put the link in, but that diagram should get you started.

what about that two wire connector on the back of the radio, what is that for? Does that power the amplifier?

those 2 wires are for constant power...ie.. for a clock...
the amp is powered by the power antenna line
in newer GM stereos, the was converted to a signal to turn on a separate motor rather than actually feeding it power. you'll have to see how your new stereo treats the power antenna option...otherwise you have to order a transistor and use an alternate power source...

I used the cigarette lighter power with a circuit to allow power to go to the amp when the radio comes on.

Does anyone know what is the max allowed voltage that can be applied to the variable resistor in the Doom Light Module?

Thanks

Voltage or Watts? The car runs on ~12 volts so everything should work in that range. What do you want to do with the slider?

Actually I forgot/missed this. if you use an aftermarket head, you will need to install a relay to power the amp as well as attaching the speaker outputs to the amp, the antenna power CANNOT power the sub amp. you will need to locate the 2 pink wires on the subamp harness and use a relay to connect them to 12 v, and use the antenna/amp wire (usually blue wire) form the aftermarket head to pick the relay. you can usually get away with using the regular radio power as the source for this, as the sub amp only draws about 10 amp max.

you dont really need a relay or anything just connect the two pink wires togather. Did the same in my fiero and the sub works great.

quote Originally posted by pontiacman63383: you dont really need a relay or anything just connect the two pink wires togather. Did the same in my fiero and the sub works great.

So your amp is always on?

quote Originally posted by pontiacman63383: you dont really need a relay or anything just connect the two pink wires togather. Did the same in my fiero and the sub works great.

ummm, the 2 pink wires come from the sub amp. connecting them together does not supply power, you have to hook them somewhere, so either it is on all the time, with a switched 12v line, or you need to install a relay.

sorry, its been a while since i have done it. you need to hook the pink wires into the yellow wire. the yellow wire is your acc. wire. so it will send power to your amp only when the key is on. do not cut the yellow wire it still need to run the the radio. So you only want to tap into the yellow wire with the pink one.

quote Originally posted by tjm4fun: you have to hook them somewhere, so either it is on all the time, with a switched 12v line, or you need to install a relay..

You dont need a relay or a switch if you know what your are doing you can hook it up so it comes on with the radio, just like the factory installed it. And this is the easyist way to do that

[This message has been edited by pontiacman63383 (edited 02-04-2008).]

Actually that line is 12v on in run and acc,it comes from the ignition switch, not the radio, so your sub would be on even if the radio is off with the car running or in the acc position. Nothing really wrong with doing it this way, except the amp will always be on when the car is running. the only way to have it only come on/off with an aftermarket radio is with a relay.

To clarify, in the stock setup with the original radio, the sub amp got it's power directly from the radio on the 2 pink wires. the original radio was designed to supply the 12v with enough current to run the sub amp. Any later model gm radio, or aftermarket radio that has an antenna power or amp turn on line cannot supply enough power to run the amp. Those lines are a signal, not a voltage source, and are usually rated less than 200ma loading. But that line can very happily pick a relay to turn the amp on and off with the radio. Don;t try to run the sub amp with that line connected to the 2 pinks, you may damage the aftermarket radio, and the sub won;t work.

If I had the link, there is a thread with a nice how to for wiring a standard 5$ automotive relay for just his purpose.

So I can buy a adaptor to install a aftermarket radio and the Performance sound will work as long as the Aftermarket Stereo doesn't over power the amp? Do I have this right? What is the Factory power for the headunit?

Wow there seems to be as many opinions on this subject as there are fieros on the road, from what I gather I'll have to use the power antenna lead on my aftermarket radio to switch the relay and draw the main power to the amp from another source? Am I getting this correct? The amplifier otherwise won't require any other connections is this correct?

i'm trying to wire my factory subwoofer to a new pontiac CD/radio, i got the relay and trying to understand what i need to do.
wiring is not my strong suit, i'm terrible at electronics and it scares me.
anyway, i found this wiring harness on ebay for the pontiac CD/radio with factory subwoofer. it is magic how this works? this is my kind of wiring, plug A-to-A and B-to-B.

any opinions before i buy this?

thanks...

quote Originally posted by 1984SE2M4: Wow there seems to be as many opinions on this subject as there are fieros on the road, from what I gather I'll have to use the power antenna lead on my aftermarket radio to switch the relay and draw the main power to the amp from another source? Am I getting this correct? The amplifier otherwise won't require any other connections is this correct?

Correct.

The antenna wire itself is not powerful enough to run the sub amp. All you will get is a thumping sound, (don't ask how I know this).

The relay will ensure that the sub amp is only on when the car radio is on, but it's easier and will save you a couple of bucks to just have the amp turn on whenever the ignition is on.

This should help, I posted this a while ago. -Jason

https://www.fiero.nl/forum/A...060206-1-053515.html

quote Originally posted by Fierofreak00: This should help, I posted this a while ago. -Jason https://www.fiero.nl/forum/A...060206-1-053515.html

i've been looking at that post for the last two days, it makes my head hurt.
i'm an idiot when it comes to electronics and wiring.

quote Originally posted by Tom Slick: i've been looking at that post for the last two days, it makes my head hurt. i'm an idiot when it comes to electronics and wiring.

That's actually a very simple setup...but if wiring is not your thing....just take the two pink wires on the subwoofer side and hook them to any power wire in the car that is only hot when the ignition is on. End of story.

quote Originally posted by jscott1: That's actually a very simple setup...but if wiring is not your thing....just take the two pink wires on the subwoofer side and hook them to any power wire in the car that is only hot when the ignition is on. End of story.

and what power would that be?

can i run a wire from the fuse block?

quote Originally posted by Tom Slick: and what power would that be? can i run a wire from the fuse block?

You could...there is a spot on the fuse box where you can connect accessories if you have the right connector. But it would be easier to just tap into the same wire that already supplies the radio.

this is the relay i bought and its harness connector.
http://www.vanco-online.com...o&products_id=100824
ok here a crude drawing of whats on the side of the relay.

code:

---

              85                                   87a         87
               |                                     |          |
-----------------------------                         \
|                            |-------------------------\ 
|                            |                          \
-----------------------------                            \
               |                                          |
              86                                         30

---

i'm only asking this question because of the harness that came with the relay.
the relay harness has 3 14ga wires (black, red, white) and 2 18ga wires (blue and brown).
red=30
black=87
white=87a (not used)
blue=86
brown=85

from what i've read this is how the relay should be wired.
85 = ground
86 = pwr ant
87 = sub
30 = 12v pwr

this is where i'm confused, the black(87) should that not be ground? plus it's a 14ga wire.
unless color doesn't matter or size. i figured that
30 = 12v pwr (red)
87 = ground(black)
85 = sub(brown)
86 = pwr ant.(blue)

i hope this makes sense to someone.

what would happen if i wired it the way i think and not the other way?

can anybody explain this to me?

thanks...

I too have the stock sub woofer, but with a after-market 4" speaker. I never got around to hooking it up (some day).

quote Originally posted by Tom Slick: from what i've read this is how the relay should be wired. 85 = ground 86 = pwr ant 87a = sub 30 = 12v pwr this is where i'm confused, the black(87) should that not be ground? plus it's a 14ga wire. unless color doesn't matter or size. i figured that 30 = 12v pwr (red) 87 = ground(black) 85 = sub(brown) 86 = pwr ant.(blue) i hope this makes sense to someone. what would happen if i wired it the way i think and not the other way? can anybody explain this to me?

Man you really don't like electricity huh? Whatever you do DON'T wire it the way you suggested or you will blow a fuse immediately.

It's very simple...here's Electricity 101

First ignore the colors. There are no standard colors on relays. I bought a handful of those harnesses and hooked them up and I was blowing fuses left and right and come to find out they all had the same colors, but some were reversed 180 degrees and I was putting power right to ground.

Anyway, the numbers are standard. All automotive relays use those same numbers, don't ask me why, they just do. A relay is just an electrically operated switch. The coil is on 85 and 86. When energized it literally pulls in a contact, (magnetically) that closes the switch between 30 and 87a.

The coil can be wired in either direction it doesn't matter, but the power antenna is the switched power so put that on 86, put ground to 85. So when you turn on your radio it will energize the relay. So now the switch between 30 and 87a is closed so you want power on one of those legs...say 30 put 12V. Any 12V it doesn't matter where you get it from, use the power going to the radio, the yellow hot at all times clock wire, the cigarette lighter, it doesn't matter. The other leg 87a goes to the Pink wire on the sub, that's what is going to power the sub.

Now some relays only are off and on so it will only have an 87. Some go both ways and are normally closed (NC) 87 and Normally Open (87a) so if your relay has 5 pins on the bottom use 87a. If there are only 4 then it doesn't matter, use whatever you have. Again, ignore the colors, it doesn't really matter.

If you need any more help, PM me and I'll give you my cell number. Good luck.

[This message has been edited by jscott1 (edited 08-19-2008).]

thanks jscott1, i wire it up the way everyone else has.