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Discussion Starter #1
I have a 85 full sized ... I just pulled the factory stereo out and to my amazement NO neg speaker connects !! WTF HOW WAS IT WORKING ? So I've been reading on the internet about a factory amp.. do I have one ??... WHERE THE HELL IS IT !!! And what wires are the correct negs for each speaker. PLZ HELP !!!

EDIT : PICTURES ADDED



As you see only one 6 wire connecter !
(PWR) (GRD) (and ONE for each speaker) !


 

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Does your factory headunit say "Premium Sound System" on it?

When you removed it, you don't have two plugs in the back - one with 4 wires and 1 with 8?
 

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get the adapter harness....you can get it from any local best buy etc
 

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Wrenching for a Livin'
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SrATEX said:
get the adapter harness....you can get it from any local best buy etc
:stupid it may take you a few trips to get the right one, but its worth it when you run across strange wiring like that
 

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Teddy Bear
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make sure when you pulled it out you didnt accidently pull the wires out of the back of the unit, i was replacing mine and couldent find the rear speaker wires and turned out they fell back into the dash
 

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Are you sure it's a factory unit,the plug in the picture looks like an after market radio plug and the radio doesn't look like a factory one.The older after market radios used one wire to each speaker,with the other wire going to chassis ground(known as a common ground system,used on low wattage output systems).Buy some good quality 14 gauge speaker wire and rewire to the speakers to turn it into a 2 wire system(Remember to remove the wire from the speakers that go to ground).
 

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wiring

run yourself all new wires. Use the wire the after market stereo using your own speaker wires. use a new ground wire, constant wire, and accessory wire. on after market radios red is for accessory and yellow is constant, just use a test light to find these 2 and the speaker outputs on the after market radio should be color coded
 

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Discussion Starter #9
Thank you.. I just got an email...

"Hello, You have whats called a negative ground system. If your installing an after market stereo you have to re wire to all of the speakers. this is the only remedy for the problem. "

So thank you everyone for your input.... looks like I got a day of pulling panels and hiding wire.
 

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Just a question, when I bought my CB it said not to hook it to a negative ground system. I know mine isn't a negative ground truck, but to someone who DOES have this system, is the entire truck on this negative ground system? Sounds like a mess.
 

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Then there are ones with one ground between two speakers. Or sometimes you can wire the two pair in parallel, if they're 8ohm speakers, depending on the stereo.

If you were around here I'd help you with all that. I did a ton of rewiring on my friend's 85 Blazer. 2 stereos, the tape deck to the factory speakers, and the CD player to 4 speakers up front and 2 amps in the back. 4 6x9s in the back and 2 10" Jensens.
 

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-Spazmatic- said:
Just a question, when I bought my CB it said not to hook it to a negative ground system. I know mine isn't a negative ground truck, but to someone who DOES have this system, is the entire truck on this negative ground system? Sounds like a mess.
You rewired your entire truck for positive ground? Because uh, I don't think I've ever seen an american car with a positive ground. Using the entire body as a ground is obviously smart because it gives you the ability to run 1 wire for power, and use the metal as the return for it. Helps a whole lot when you're running 1/0 or larger.

As for the head unit, look at your speakers, if the neg end of the speaker connects to your body somewhere, then your speakers are using a common speaker ground. It can be done, but it's usually pretty crappy. You'd have all kinds of noise problems... if you really want to be smart, run all new speaker wire. Doesn't have to be the expensive stuff, just plain on 16/2 from radioshack.
 

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My friend has a John Deere B with a positive ground, but it's real old, '37 or something.

Ya, I've never seen vehicle wiring as a positive ground.
 

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Old school and some new but CHEAP (roadmasters and no names) radios use a common ground. Your best bet is to replace the wire with +/- and the radio.

Bronco4Life said:
Doesn't have to be the expensive stuff, just plain on 16/2 from radioshack.
:twotu:
 
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