I have just rejoined the dwindling group of Fiero owners after a ten year hiatus.

I just put a partial payment on a 1987 GT which now sports an aftermarket (Pioneer) radio. I do like the idea of having a system which can play CD's, but I would rather have something that blends in with the dash.

I would like something that can use the original wiring harness with no alterations necessary. I'm looking for recommendations, if in fact such an animal exists.

John W
Baltimore

There is a stock-looking CD player, but it needs an adapter harness. Not hard at all



UP3 code stereo, found in 98-02 Trans Ams, Sunfire, etc.

Go to www.replacementradios.com
There are several later GM head units available that will fit our cars.
The wiring will be different, but there is a plug 'n' play adapter available that will save your original wiring from being cobbled up.
(RWDPLZ beat me to it.)

The most popular swaps for the Fiero are here.
http://replacementradios.co....php?cPath=21_42_204
I have the second one down.
If you want to connect an XM radio, iPod or other external device, it or the 5th one down (the Monsoon) is the way to go.

The first two do not have red backlighting. At least mine doesn't. They came from Chevy/GMC trucks.

Here's mine. (Not really a good pic. Sorry.)

[This message has been edited by Raydar (edited 05-12-2012).]

https://www.fiero.nl/forum/Forum2/HTML/122625.html

Here is a thread with more choices.

I'm thinking about changing out my stock cassette player for a Delco "2001 Series" UP3 or U1C. No use for cassettes anymore and modded CD players with jacks for MP3 input are available on eBay for reasonable prices. I see RWDPLZ's unit in this thread has the Magic Jack. "Artistmac" on YouTube has a nice HowTo video done with the cassette version of the series (UN6).

...and... on top of everything else, that blue they used in the stock digital clock has always looked like crap against the rest of the rad dash lighting.

But before I leap into this project, a question....

The stock stereo speakers are supposedly 10 ohm in the dash, 4 ohm in the side pillars.

The 1994 Camaro/Firebird Service Manual (those cars were equipped with the 2001 Series) says 4 ohm speakers were in the doors with 10's in the rear, and the Pontiac UP3 package had 10 speakers around the interior.

Does the easy "Plug and Play" 12 to 20 pin adapter available for these upgrades account for which wires should be going to the correct speakers as far as the correct ohm rating (impedance) ? Should the fronts be changed out so it's 4 ohms all around with these head units ? Or leave things as is ? Does it even matter at all ? Just go for it and whatever smokes, smokes ?

First , many thanks to those who posted links. I never considered getting a GM original. Wow! A lot of those radios look just like the ones in my previous Blazers and my 2002 Tahoe. The Monsoon with the ability to hook in an MP3 player or iPod is exactly what I want. Now that University of Texas made "the Music Die" on 98.9, I have to bring along my own. Was using a cassette adapter until the 25 year old rubber finally gave out.

You can run just about any speaker impedance on any radio. Performance may suffer, but it will put out sound.

That said, my 88 had 10 ohm speakers in the dash. Not sure what is in the back. I got the replacement speakers from Rodney Dickman for the dash and they work just fine even though they are less than 10 ohms. Rodney's speakers are 8 ohms and work just fine. His web site says the rear are 4 ohms and you should have no problem replacing them with new 4 ohm speakers.

You won't hurt any Delco radio running anywhere from 4-10 ohm speakers. They're as bulletproof as you'll find.
My headunit (pictured poorly, above) is driving 4 ohm Pioneers in the dash and whatever the stock rear speakers are. (They still sound decent.)

This is the best matching, most accurate GM Delco stereo that you can find. It uses the 21-pin connector, plays CDs, and it matches EXACTLY the interior found in the 1985-1988 Pontiac Fieros.

They were first offered in the 1989 Pontiac Bonneville SSE, when ordered with the 8-speaker premium sound system and steering wheel controls.





EDIT: As for using the factory wiring... if you have a Pioneer CD player in your car, chances are the factory wiring has already been hacked up. That said, if you do decide to repair the factory harness back to stock, it's easy to find a 9 pin to 21 pin harness adaptor.

[This message has been edited by 82-T/A [At Work] (edited 03-26-2013).]

Thanks to those that responded to my questions on Delco radios and speaker ohms. I feel better about taking the plunge, if the units are as durable as Raydar thinks. I won't be blasting it at full volume anyway.

But I'm a still a little mystified as to why Pontiac audio engineers went with the 10 and 4 ohm mix of speakers in the first place.

Possibilities .... Either:

1) The amp was intentionally designed to handle any speaker between 4-10 ohms placed anywhere in the car.

2) The amp circuitry and wiring going out to a particular speaker position is designed for a certain ohm rating, and that could be different for every year and model of Pontiac ( maybe why model UP3 has umpteen different GM part numbers associated with it).

3) The Pontiac engineers were totally incompetent. Maybe 10 ohms were the cheapest bananas on sale that day.

Since my last post I tried educating myself on the amp/ohm/speaker thing and came across this on the Olds Toronado site ( now there's a group we can all have empathy with.... )

http://www.toronado.org/FAQ/GenI/mikesir.htm

The paragraph on Speaker Resistance basically says the difference between a 8 or 10 speaker is negligible, and the only bad move (as far as amp wear & tear) would be to place a 4 ohm speaker where a 8 to 10 ohm speaker is expected.

I know I'm over-thinking all this because because I want to get the setup right, especially if I go through the trouble of replacing the front speakers. Rodney Dickman's 8-ohm speakers would be the "most correct" new option for the fronts, but I could do that and potentially have it all ass-backwards with the new Delco in. ( maybe Rodney knows all this and has a good laugh on his way to the bank after each speaker order )

Is there a method by using a multimeter on the wire leads left in the hole after the old speaker comes out ? ( "Eureka ! This is where an ??-Ohm speaker gets dropped in !" )

It's too bad TLG-Auto doesn't offer their speaker adapter plate with woofer+tweeter+crossover pre-installed. 2-ohm speakers and tweeters exist, so in various combinations there could be something for everybody from 4 to 8 ohms total per side.

The long downfall of General Motors was on it's way during the production of the Fiero. The way they selected parts was:

1. the cheaper the better.
2. negotiate a 40% reduction in price.
3. Use the vendor you used last time.

edit: I installed Rodney's speakers and they appear to perform as a stock setup would, but the audiophiles among us recommend adapter plates for round 5.25" speakers as a more modern solution. Perhaps it is, but nobody has worried much about ohm imbalance; I guess you just turn the knob a little to get the balance you want.

[This message has been edited by Gall757 (edited 03-27-2013).]

Sounds like you are asking for the gory details.

Here is the engineering answer:

There is a thing called damping on both amplifiers and speakers. It has to do with what happens when the voltage on the speaker coil changes. To some extent, impedance matters because lower impedance will draw more current, but as someone said, most amps are pretty bullet proof in this regard. It really is a matter of how much volume can you get and what kind of frequency response do you want. It also might affect the relative balance between front and rear, but you have a knob for that.

There are probably three reasons for using 10 ohm speakers from the factory:
1) the radio technology is still 1970's vintage and the transistors work better with more impedance in this amplifier. Remember, these cars were built only about 12 to 15 years after the industry fully switched over to transistors in the radios.
2) it is really hard to get a speaker to work in the 4x10 format at lower impedance (could be wrong on this one)
3) They had a bunch of 10 ohm speakers laying around from the most recent run of Chevettes

A 4x10 speaker is an abomination that is there to be able to fit the dash form factor. It starts off being a monumental compromise and is not high fidelity. It is really hard to get any kind of cone movement and frequency range with such a mechanical system. You will notice that top end vehicles all use round speakers and make a place for them. They don't even use 6x9 which is marginally better than 4x10 but not by much.

Using an adapter plate and 5 1/4 speakers will get you better fidelity, but with 59 year old ears and all the noise in a Fiero, I can't tell the difference. I *do* want to put in a powered sub-woofer at some point. I felt around behind the radio area and there is a movable piece of plastic that I am guessing is where a sub woofer would be installed.

Thanks much for all those truly gory details, Ray_and_kevin. So much good information has overloaded my circuits.

But I'm reassured to the point where I'm not going to fret about the impedance so much.

My 4x10's are 25 years old now and will need to be replaced someday. The new head unit is likely to expose their age. I've read about the 5.25" round speaker adapter that was developed by fierosound and there's a version of those being sold by TLG-Auto. Anyone know of a brand/model of 2-way 5.25" speaker that drops in to the adapters and fits without having to do any trimming of the dash ? I've seen some Rockford Fosgate and Massive models that are more compact/shallow than average but maybe nothing fits without at least some dash trimming.

My ears are 59 years old also. What are we doing running around in these kid's cars ? Shouldn't we be in Aston Martin's by now, passing the Grey Poupon ?

Hey, my ears are 79 years old and I thought that I was too old for Fieros twenty years ago, so I sold my 88GT. More recently, I felt the urge again to buy a car that required a lot of bending and twisting to get in so I bought a 87GT.

John W
Baltimore