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So it connected the wires back to where they were originally. So all good there. I pulled the head unit and tapped into the left front channel speaker wires from there.

Now on the left channel of the RCAs i am seeing the same voltage as the right channel, 3V...but the left channel is showing -3V. I rechecked the wiring and its all positive to positive and negative to negative, so im not sure why its -3V. Should I switch the positive and negative wires where they connect to the RCA adapter?

Another wierd thing..just before i cut the left channel wires and soldered my speaker cables to them, the head unit played music through the rear speakers fine since that wiring was untouched from stock. But once i wired in the left channel wires, the rear speakers became silent. I didnt touch or mess with the rear speaker wires at all. My RCAs seem to be getting voltagefrom both front channels, so im not sure why the rears suddenly stopped working. Any thoughts?
Is your meter set to AC? I don't think my meter shows negative voltage with AC, only DC (it's a pretty basic meter though).

You shouldn't be cutting OEM wires, ever. I'm a bit concerned that you're in over your head, and are risking some big problems. If you don't want to use a proper wiring harness, you should at least be using good wire taps, not cutting wires.
 

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Discussion Starter #22 (Edited)
Is your meter set to AC? I don't think my meter shows negative voltage with AC, only DC (it's a pretty basic meter though).

You shouldn't be cutting OEM wires, ever. I'm a bit concerned that you're in over your head, and are risking some big problems. If you don't want to use a proper wiring harness, you should at least be using good wire taps, not cutting wires.
Ah, yes, i was setting it to DC, will test again set to AC. It was a late night and i was still working on the car at 2am.

Maybe I should take it to the local audio shop and have them look at it. Should i have them just put in an aftermarket head unit or just have them fix these issues? I would like to keep the stock head unit if possible for cleanliness.
 

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Maybe I should take it to the local audio shop and have them look at it. Should i have them just put in an aftermarket head unit or just have them fix these issues? I would like to keep the stock head unit if possible for cleanliness.
It's hard to say, I don't know what you've done and whether or not it's a simple fix. An aftermarket head unit will almost always be better in every way (except aesthetics) than an OEM head unit. There's a very real chance that you OEM head unit doesn't even put out a flat, unprocessed, fullrange signal, so by the time you get the signal to the speakers, who knows what's been done to it.
 

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Discussion Starter #24 (Edited)
It's hard to say, I don't know what you've done and whether or not it's a simple fix. An aftermarket head unit will almost always be better in every way (except aesthetics) than an OEM head unit. There's a very real chance that you OEM head unit doesn't even put out a flat, unprocessed, fullrange signal, so by the time you get the signal to the speakers, who knows what's been done to it.
At this point I have corrected my wire cutting stupidity by reconnecting everything i cut. The only change in the wiring flow now is where I cut the stock left front channel speaker wires behind the head unit to attach my speaker wire to RCA left channel and where I cut the stock right front speaker wires by where they enter the door for my RCA right channel.

I guess i could either take it to a shop and have them figure out the reverse polarity in the left channel rca and the rear speaker issue. Or i could just reconnect all the stock speaker wires to themselves then buy an Alpine head unit and just use the RCA outs and use a metra wiring harness for the connections.
 

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Discussion Starter #25
At this point I have corrected my wire cutting stupidity by reconnecting everything i cut. The only change in the wiring flow now is where I cut the stock left front channel speaker wires behind the head unit to attach my speaker wire to RCA left channel and where I cut the stock right front speaker wires by where they enter the door for my RCA right channel.

I guess i could either take it to a shop and have them figure out the reverse polarity in the left channel rca and the rear speaker issue. Or i could just reconnect all the stock speaker wires to themselves then buy an Alpine head unit and just use the RCA outs and use a metra wiring harness for the connections.
So ive rewired everything back to stock. No sound comes out of the rear speakers still for some reason. But im having the local well-known audio shop install an Alpine ILX-W650 into my car and i am going to run RCA from the preouts to the amp, bypassing all that mess. The shop mentioned though that these Mazda 2s have a canbus wiring system in them. So maybe thats why everything in this cars wiring is wierd and doesnt make logical sense to me (im used to working on 90's era cars. They said it needs a $200 canbus system interface in addition to the normal wiring harness adapter. So its expensive, but at least it will be finally done. Does that all sound right?
 

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Discussion Starter #26
So ive rewired everything back to stock. No sound comes out of the rear speakers still for some reason. But im having the local well-known audio shop install an Alpine ILX-W650 into my car and i am going to run RCA from the preouts to the amp, bypassing all that mess. The shop mentioned though that these Mazda 2s have a canbus wiring system in them. So maybe thats why everything in this cars wiring is wierd and doesnt make logical sense to me (im used to working on 90's era cars. They said it needs a $200 canbus system interface in addition to the normal wiring harness adapter. So its expensive, but at least it will be finally done. Does that all sound right?
Update: i was letting the car run for a bit and about 5 minutes later the sound system mad a pop noise and then started working again. Full sound to the rear speakers now. I guess it had to realize the speaker wires were normal again.
 

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Update: i was letting the car run for a bit and about 5 minutes later the sound system mad a pop noise and then started working again. Full sound to the rear speakers now. I guess it had to realize the speaker wires were normal again.
That could be true... the computer may have shut off those outputs becuz they were in error mode, but eventually checked them again and found they were functional.

As for the price of the CANBUS harness, that sounds about right... maybe even a little on the cheaper side. But if u'r adding an aftermarket HU, why do u need to integrate into the factory wiring? What will be powering the speakers (HU, aftermarket amp, or factory amp)? Maybe it's for a switched power source so the HU will turn on and off w/ the car?
 

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Discussion Starter #28
That could be true... the computer may have shut off those outputs becuz they were in error mode, but eventually checked them again and found they were functional.

As for the price of the CANBUS harness, that sounds about right... maybe even a little on the cheaper side. But if u'r adding an aftermarket HU, why do u need to integrate into the factory wiring? What will be powering the speakers (HU, aftermarket amp, or factory amp)? Maybe it's for a switched power source so the HU will turn on and off w/ the car?
A 4 channel amp will be powering the front stage and sub. They said the car's canbus system check in with the stock head unit as well, so this canbus interface gets the car the info it needs. But yeah, other than the HU getting power from the car and being connected to the antenna, the audio system will be its own seperate system.
 
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