Sean Moore

Hello - this is my first post on the forum. I've gained tremendous knowledge reading and finally have a need to get some help.

I'm in the midst of replacing my fan switch and radio on a 1972 Cutlass Supreme Convertible. It appears that the folks that had this previously (or those that did some interior work) did not hook everything back up when they wrapped up... So I'm in the process of learning about my new toy.

Can anyone tell me what this blue wire is for? It apprears to be coming out of the right hand side center - right behind the stereo.

Thanks for the help and ask me any clarifying question as I'm clearly a newbie here.

Sean

BeenThere

That looks like the rear speaker wire.

Sean Moore

Hi BeenThere - thanks for the quick reply. Take another look at the pic. I think that you are referring to the white wires not the blue one that I'm holding. Note it is a single wire.. not any speaker wire I've ever seen was single.. typically a pair of positive & negative. Thanks appreciate you taking another shot at this.

Sean

steverw

I think BeenThere is right, my car also has only one blue wire that IS the rear speaker wire. I think it grounds to chassis.

oldspackrat

Been there is 100% correct. On these older cars it is only the power wire that goes to the speaker, they are grounded to the car where they are mounted. In this case it is the rear package tray area. If you look in the trunk on the passenger side you may see the other end of that blue wire.

Sean Moore

Thanks guys - this is really helpful! I'm going to see if I can get those hooked up! Do I hook up the positive to the blue wire and just leave the negative unconnected?

Thanks again for your help!

Sean

joe_padavano

The factory radios were designed so that the speakers used chassis ground for the return. That's why there is only one wire - the body served as the other "wire". This usually will NOT work with an aftermarket stereo, where the speaker circuits are separate from chassis ground. Tying the speaker return to ground may blow the amp. You will need to use a different speaker and dedicated wiring if you are using an aftermarket stereo.

Sean Moore

Thanks Joe - really appreciate you saving me from blowing anything. Appreciate everyone's help on figuring this out.

Best,

Sean

cjsdad

The blue wire is the rear speaker wire like mentioned above. If your new head unit is a low-powered unit you can successfully use the factory wire and ground the (-) speaker lead at the rear of the car. If the new head unit is rated anything above 6 watts per channel it is considered to be a high-powered unit and cannot use a common (chassis) ground. Any time an aftermarket stereo unit is used, it is best to install new speaker wires, front to back. This removes the possibility of mistaking the wrong wire for a speaker wire. Just don't put a screw through the new wires! This also preserves the factory wiring in case you ever decide to restore the vehicle to like-new condition.