Speaker grounds

[87GrandMarq]

Im splicing in a new connector for the radio because the old one was cut out for some reason but I noticed there are 4 speaker grounds that are all black with a white stripe. Does it not matter which pin they go to? Im assuming no but want to be sure before I go crazy.


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[DerekTheGreat]

Sounds like you've got turdy common ground. My '85 was that way and the answer is: No, it does not matter. If you care about sound quality you'll want to consider running new speaker wire to each speaker and then to the head unit/amp like it should be and was 88+. Least that's how my Town Car is and it's an '88. Maybe the Ford and Mercury cars were different.

[sly]

The 88 MGM I had was 2 wires to each speaker (not common ground). If you are splicing in the newer 8-pin connector, you will want to ring out which ground is connected to which speaker. If you're splicing in the older 5 pin connector, you just tie all of those grounds together. Sounds like someone put an aftermarket stereo in previously and used a multimeter to figure out which wires were connected to which speaker.

If you're putting in an aftermarket stereo, you will have to figure out which wire pairs up with which speaker. Connecting them wrong could blow up the new stereo. Also, check to see if the grounds are connected to chassis ground. If they are, you will have to run new wire to each speaker for an aftermarket stereo.

[bgreywolf]

The radio wiring (at least in '86 and '87) varied widely with which radio it came with. It's generally easier to run new wires than try to make sense of it.
I thought I had scanned pages from the '87 EVTM Radio wiring manual but I can't find them to upload.
The common ground can cause problems with some audio equipment--it should say in the manual--but if you're putting the factory radio back in you should be okay.

If you don't have a meter, use a 9V battery and tap the leads against the 2 terminals. You'll hear a little "click" noise from the speaker that the wires go to. Don't hold it long, speakers don't like DC, just a fast tap a couple times until you can tell which speaker it is.

[87GrandMarq]

Speaker grounds

Im not sure which one it had from the factory but Im assuming its probably the 4 button memory or something because its not a base model but its also not the high end. Im installing a stock head unit. Im thinking its a good idea to check which ground goes to which speaker just in case I want to add an aftermarket radio one day, unless I rewire all the speakers. Thoughts?

Before I forget yes it has the two 8 pin connectors, Im wiring the black one in. That one has 4 + and 4 - for all the speakers. The positive side was easy since theyre actually color coded but all the speaker grounds are black with a white stripe.


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[bgreywolf]

Yes, find where each pair of speakers goes. The difficult part of the common-ground stereo is that there is a splice where all four of those black/white wires are connected. However! It's possible that the reason the connector was cut off, was to cut the splice out. If that's the case, each of those wires really does go to only one speaker, and you're golden. To test, use the 9 volt, touch all 4 of the colored speaker wires to one terminal, and then tap 1 of the black/white wires. If all 4 speakers click, the splice is still there. If only 1 speaker clicks, you know which speaker that black/white wire goes to.
I don't know where the splice is located, but I would guess it's pretty close to the connector that was lopped off, so it very well might be gone.

[gadget73]

No idea what you have since neither of the wiring diagrams I have for an 87 have more than one black/white wire. This is what I've got though

[87GrandMarq]

Ill try the 9 volt battery trick thanks and thanks gadget. Ive attached a few pics of the harness Im splicing and the other harness for reference.


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[sly]

I'd definitely take a meter to the black/white wires and make sure they're not all tied together or tied to chassis ground first. No sense in blowing up amp chips. Then just use the meter, if they're all infinite resistance, to figure out which positive wire they're paired with by finding the one that fives a resistance value around 3-8 ohms. Can't remember what stock speakers ring out to.

[87GrandMarq]

Great advice thanks. The wire colors pretty much lined up to what I pulled up on google it was just the grounds but its better to be safe than sorry!


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[IPreferDIY]

Good words to live by.

[bgreywolf]

Better late than never? Wiring from '86 EVTM for low-end common ground stereo.