Wiring in aftermarket speakers in a 78 using original wires-need correct polarity

[Rick M.]

Have a 78 PC with the 4 speaker radio. Car came with cheap aftermarket speakers and wiring was a mess. A PO ripped all the factory speaker wires out and used regular store bought wire so have nothing to go by. I put all new Lectric Limited wiring harnesses in. They come with the connectors that snap onto factory speakers, which I don't have. I bought all 4 Electro-Tech replacement 10ohm speakers but they just have the plus & minus prongs. Looking for what factory colored wire goes to positive & which to negative so speaker polarity is correct. If any of you have that info, would sure like to know. Thanks
RM

[David H.]

Re: Wiring in aftermarket speakers in a 78 using original wires-need correct polarity

Have a 78 PC with the 4 speaker radio.... ... Looking for what factory colored wire goes to positive & which to negative so speaker polarity is correct. ... RM

Rick

Wiring Diagram shows:

Left Rear Speaker with circuits (wires) 116 and 199. 116 is a Yellow wire. 199 is a Brown wire.

Right Rear Speaker with circuits 46 and 115. 46 is a Dark Blue wire. 115 is a Light Blue wire.

46 is described as "Dark Blue" "Rear Seat Speaker Feed from Single Radio or Right Stereo"
199 is described as "Brown" " Rear Seat Speaker - Feed from Radio Left Stereo"
115 is described as "Light Blue" "Speaker Return, RT rr Stereo"
116 is described as "Yellow" "Speaker Return, LF rr Stereo"

Diagram shows all wires as 18 gage.

So...., no plus and minus. Sorry - not much help. At least you can be consistently wrong!

Dave

[Rick M.]

Re: Wiring in aftermarket speakers in a 78 using original wires-need correct polarity

What I have...
Yellow & Brown=left rear
Dark blue & Light blue=right rear
Purple & Tan=left front
Dark green & Light green=right front
Maybe there is a test one can do to determine plus & minus? (Feed would be + & return is -)?

Am hoping someone here has dealt with this before and kept notes.

Also need to decide whether to cut off the factory type connector ends and attach the spade push-on terminals for new speakers or keep the those and rig up some adaptor jumper wires.

[Tom R.]

Re: Wiring in aftermarket speakers in a 78 using original wires-need correct polarity

Also need to decide whether to cut off the factory type connector ends and attach the spade push-on terminals for new speakers or keep the those and rig up some adaptor jumper wires.

Back in February, replaced front and rear speakers with the "correct" 8 ohm types. But yes, had to cut those factory connectors off the harness and used the spade-push-ons. I concluded the best way to get the correct polarity is to follow the original connections. You'll see the rears in the photo. Somewhere I read that the darker color was positive. Zoom in and you'll see the red connector corresponds with a red dot on the backside of the speaker frame.

rear speaker & Polarity.jpg

[Kurt K.]

Re: Wiring in aftermarket speakers in a 78 using original wires-need correct polarity

Rick, If you are using a factory radio it will have the wire connections listed on the radio where the wires connect. If you are using the aftermarket radio, you just need to have all the speakers in phase. To check, use a 9 volt battery and connect it to the speaker and notice which way the cone moves. They will push up or go down in the housing. You want all the speaker cones to move the same direction. I mark the speaker wire as + where the + side of the battery pushes the speaker out. As long as you have all the speaker wires that are + on the same side of the circuit, you should be in phase. The speakers will play either way, just the sound is much better when all the speakers are in phase.

[Rick M.]

Re: Wiring in aftermarket speakers in a 78 using original wires-need correct polarity

I looked at my radio(actually a 79 Delco AM/FM cassette unit) and see nothing in the back that would denote speaker polarity.

[Kurt K.]

Re: Wiring in aftermarket speakers in a 78 using original wires-need correct polarity

My 79 AM/FM Stereo had it on the unit. It may be on top? Look up 78/79 Delco radio's up on ebay, some show on the case the wiring positions for all the wires going into the radio.

[Rick M.]

Re: Wiring in aftermarket speakers in a 78 using original wires-need correct polarity

Yeah, the 79 radio I bought has the original wire plugs for power, front & rear and about 4 inches of wire coming out of them. And the new harness has the same plugs so GTG on that part. It's what color wire goes to which speaker terminal I'm wondering about to have them all in phase. Might have to bench test and watch the cone movement as radio is playing and try to make them all match?
My radio just has the ID part # info sticker on the side.

[Kurt K.]

Re: Wiring in aftermarket speakers in a 78 using original wires-need correct polarity

If you look straight at the radio where the speakers wires clip in. The side that has the bump outs on the connection clips are the + side.

+RR RR-
+LR LR-
+LF LF-
+RF Rf -
Lamp ANT
GND 12v

Your wire color should be correct with the new harness, and you should be able to tell the + and - side by the color of wire coming out of the radio at these positions.

[Rick M.]

Re: Wiring in aftermarket speakers in a 78 using original wires-need correct polarity

Here are some pics of what I have. I had this radio built 15-16 years ago and been sitting in the box since then. Car is getting a refurb so now time to install it. Have a ton of cassettes but no 8 track tapes and figured at the time I bought it that very few people would know it's a 79 radio. If you look close just to right of the volume knob, is a jack to plug an iPod in. Old tech now. And my iPod is long gone.
The guy that built the radio could have used parts from many different radios. The connectors in it now are what the guy gave me. The harness I bought matches up so a direct plug-in.
IMG_2038.jpgIMG_2039.jpgIMG_2042.jpgIMG_2041.jpg

[Rick M.]

Re: Wiring in aftermarket speakers in a 78 using original wires-need correct polarity

I hesitate updating this as I feel a bit foolish in not seeing the answer that was right in my face. All I had to do is turn the unit over and there the answer was. As Kurt K said. I still needed to verify the wire colors and where they went. That is when I noticed a mistake in the 1978 Corvette Electrical Troubleshooting Manual. At least the copy I have. Page 13 shows the radio & wire schematic. The yellow and brown wires are reversed. Everything else is correct. I made up a chart showing what wires go where. Should apply to 78 & 79 radios with 4 speakers.
IMG_2046.jpgIMG_2045.jpg