Line level help troubleshooting signal voltage-which is negative/positive?

[bigmizzle99]

My OEM signal input for Front and Rear each have 4 wires for each Left and Right...there are no RCAs, just a connector They are not labeled and the owners manual special AV section doesn't match what's in my car.

Each input cable has a Red-Black-Green-White. I need to figure out which is positive and which is negative. How can I do this?

[bigmizzle99]

bump for help.

I think I can measure VAC on the DMM. I can put the red probe on the source wire(s) but I'm unsure where to put the black probe for meaningful measurement...I'm going to try to use chassis ground.

I know its an unusual request, most people don't have to figure this out. I emailed Tony D at D'amore, too. Hopefully he can help.

[Tarball]

more clear description would help. I get the basic question but how many wires are are we talking in total here? Can you look at the speaker and at least give us the color codes per channel. Make it very clear which color wire what channel that goes too -front left etc

LIke this

Front Left -

Wire 1 - Black with Red Stripe

Wire 2 - Green with White Stripe

etc etc.

Year make and model helps too

[bigmizzle99]

thanks for helping.

Its not speaker wire, its line level analog (like pre-outs on an aftermarket HU) except with OEM it has no RCAs, its connected to a "molex" style connector. these pre-outs connect the HU to the OEM amp (its Bose)

these OEM pre-outs are for Left and Right and each of these OEM pre-outs has 4 wires (2 each for front and rear speakers, I'm not sure the combination, but I think Red-Black and Green-White are the combinations) I will worry about which is front/rear/left/right later, but for now I need to figure out positive and negative.

[Stephen13]

You won't be able to determine phase with a DMM. Without a schematic and/or wiring diagram I'd say your only option would be to connect an O-scope to determine your positive and negative wires.

When the scope's red probe is connected to the + wire the display on the scope would look like the sine wave image below (positive going voltage first). If the red probe is on the negative wire the display on the scope would be flipped (negative going voltage first).

[bigmizzle99]

Hmmm, ok, thanks bro. Don't have an O-scope.

I do have the AV and Nav System manual from Nissan for my car. Its not a 100% match for what I see in the vehicle, but after looking it over again today with what I learned after tearing apart the wiring harness last night, I think its more accurate that I originally thought. The pin out placement in the connectors is not a match, but almost all the colors are...so, I *think* I have the polarity right...its at least a starting point.

Thanks for looking.