Checking polarity from HU

[Mordant80]

Is there any way to check the polarity of the speaker wire coming from the head unit using a mulitmeter? I think I know the answer but a buddy of mine swears the opposite of what I think. If you can check this with a MM could you describe how and if not describe why not? Thanks in advance.

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[Mordant80]

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[SethPhillips 5,000+ posts]

not with a multi meter.. you can check the resistance with it, but not polarity..

use a 9v batt, and if you can see the speaker, it should "pop" outwords if it's in phase.

and will "pop" in if out of phase.

 

[Mordant80]

I'm not talking about the speaker itself. Say I've got the door taken apart and I threw the speaker out (hypothetical). Would there be a way to figure out the polarity of the two wires hanging out the door without the speaker and without looking up the schematic.

 

[Mordant80]

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[aussiek2000 10+ year member]

normally negative has a black stripe on the wire.

 

[Mordant80]

Yea, but is there a way to test it?

 

[Mordant80]

Bump

 

[djman37 5,000+ posts]

manual?

google for one if you don't have it?

 

[SethPhillips 5,000+ posts]

I'm not talking about the speaker itself. Say I've got the door taken apart and I threw the speaker out (hypothetical). Would there be a way to figure out the polarity of the two wires hanging out the door without the speaker and without looking up the schematic.

nope. you need a wire diagram.. unless it is after market wire routed into the door. then it would be the black or black/w a stripe..

 

[Mordant80]

Alright, thanks for the info.

 

[djman37 5,000+ posts]

you COULD make a .2hz sine wave that only goes through the + half of the cycle....that MIGHT work.

 

[Mordant80]

hehe, yea, that might do it. Basically what happened is i had my buddy helpin me replace my stockers. Find out they aren't labeled so he grabs a multimeter, sets it to ohms, and procedes to check the resistance between positive and negative to ground on the car (a bolt in the door) Comparing the two readings told me which one was negative. I was like huh? how many ohms. He said alot. I tell him I don't understand how he came up with his answer and i'd like to double check it by getting a diagram and he says, trust me. I'm like, I don't know man. So he says he's not gonna help anymore since I don't trust him. But it had me wondering, since he felt so strongly about it, I wanted to see if he knew something I didn't.