87 R1500 Retro sound radio

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ItalyVargas12

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Hey guys! I bought a retrosound radio for Rosie, does anyone know what the wire color meanings on my factory radio are? The retrosound radio came with tags, so that side is easy. My truck is the 1987 GMC Sierra Classic. I appreciate all the help!
 

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85Sierra Classy

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Not sure on the wire colors, but when I bought and installed my retro sound, a jumper harness was available that plugged right into the factory radio harness connector, and connects to the new radio with instructions. I remember it being very simple. Based on their catalog now, 70-1677-1 is the part number I used. Hope this helps
 

CalSgt

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Not sure on the wire colors, but when I bought and installed my retro sound, a jumper harness was available that plugged right into the factory radio harness connector, and connects to the new radio with instructions. I remember it being very simple. Based on their catalog now, 70-1677-1 is the part number I used. Hope this helps
I don't know how many times I've had to fix other peoples botched stereo installs when they would cut the factory harness out of late model cars that all had adapters available. If there is a harness adapter available they are worth the cost.

If theres no factory harness connecter or if someone has clipped it off you've got some work to do, label wires with each step:

With the key off test each wire with test light for the battery +

With the key on acc. test each wire for the ign. hot wire

Take a 9 volt battery hold one terminal of the battery on a wire then tap each other wire on the other terminal until you hear a speaker make noise. Do this until you have a pair for each speaker.

last wire left should be the ground, if no wire is left the ground was through the chassis of the radio to the dash or through a bolt supporting the radio in the rear.

if more than one wire is left:
There could be a wire to dim the screen/lights when the headlights are on. More common in late model cars. There also could be wires to turn on an amplifier or motorized antenna if equipped or available as an option from factory..

figure out the polarity for the speaker wire pars: watch the speaker while you connect the 9V battery, if the cone moves out then the way they are hooked to the 9V battery is correct. Positive wire on the + battery terminal. If not switch the wires and test again to be sure.
 

ItalyVargas12

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if the cone moves out
What do you mean the cone? I'm thinking I'll head outside and try the way you suggested, I'll cut off the old harness but do it far enough back that I could rewire it later if I end up getting the factory radio fixed down the road
 

shinkle

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Attached is a snip pic from the 1987 R wiring harness linked in reference section of this site.

Are you sure you want to cut the harness instead of finding an adapter ?






You must be registered for see images attach
 

Redfish

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I suggest checking on the adapter for the factory wiring. That's what was done to my '87 by the previous owner and it made for a nice, slick installation. It cannot cost much $$ and it will save you a great deal of aggravation.

If you are having trouble understanding the post by @CalSgt that tells me the adapter is a perfect idea. Yes, it is just a radio but if you have spent the money for it and you want this truck to be nice, why not make it perfect?

What he said about the dimmer/light wire bit me pretty hard on a '73 Bronco project one time. I completely re-wired the Bronco and a few weeks later all the parking lights/running lights would come on as soon as the ignition was turned on. The instrument cluster lights were always VERY BRIGHT and the dimmer did nothing. I knew I had wired all of that properly. Turns out that another friend had installed the Retrosounds Radio and had tied in the "light" wire to the switched (ignition) power wire. This backfed through the rheostat for the dimmer control.

Good luck with your installation.
 

Corvette Ed

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What do you mean the cone? I'm thinking I'll head outside and try the way you suggested, I'll cut off the old harness but do it far enough back that I could rewire it later if I end up getting the factory radio fixed down the road
Trust me you don’t want to cut the harness,get the adapter.
 

Snoots

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I'll cut off the old harness but do it far enough back that I could rewire it later if I end up getting the factory radio fixed down the road
NO!

You must be registered for see images attach
 

Redfish

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Heard! I'll find the adapter
Excellent!

I am obligated to say that the wires can be spliced, they can be traced, this job can be done the same way it would have been done and has been done back when these trucks were new. This is wiring, not hieroglyphics, it can be figured out. There is no mysterious secret to these wires. It is just a radio and speakers.

However, the installation will be cleaner, neater, and will be easier to swap out down the road if you or someone else ever swap out that radio.
 

RoryH19

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Speaking for your truck, do not cut or splice the harness. Use an adapter like this.
The three factory plugs go into the black connector and the new radio is connected to the wires.
 

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TPISly-C10

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black plug: yellow ignition, black ground, grey dimer light
white plug: front speaker, grey/brown Left- green/light green right
blue plug: rear speaker, bleu/light blue left, yellow/dark brown right ;)
 

ozone160

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Here's pics of the package I saved in case I needed it again. The harness i used in my 87 is Schosche #GM01.
 

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S1NN3R

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For any of you that have installed this Retro Radio, which radio did you buy? I'm looking at the M2A from them and was really wondering about the sound quality.
 

chevytech87

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I’ve got one in my 87. The metra harness is labeled accurately (surprising) and was 100% worth it. Makes it easy to take things in and out. Cut factory harnesses are gross, just say no. I’ve been super happy with the sound quality of my unit, that being said the sound system is a work in progress. But for what’s currently in the truck, it does well. Bluetooth works well too, no loss, no chop, doesn’t drop connection all the time. Well worth the $$
 

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