99 Ford Expedition, noise problems

Thanks for the info geep, I honsetly would have just started pulling wires and re-running them, really should have thought of this but thank you for saving me hours on this.  So when I ohm them out I just get a 4 ohm reading on all of them correct?  would I see something closer to 0 ohms if they are in fact ground out on a given channel?  I will check all of these the second I get a chance to, that car is at my other house which is about 40 miles away so I probably wont get to check on these and let you guys know what happens for like a week or so.  Thank you for all of the help so far, I really appreciate it.

Jeff

maybe, maybe not. A black oxide screw going through speaker wire into a painted surface may not have 0 impedance to ground. It could have just enough potential to cause noise but not enough to change the impedance of the speaker.

He's right, it won't necessarily be 0 ohms, but it will be significantly less than 4 ohms.  First ohm the speaker wires while disconnected to read the speakers individually.  Then check the leads seperately for a short to ground- touch one probe to a speaker lead, the other to the amp's ground terminal.  Be sure to do this with the leads disconnected from the amp though, so you don't get a false reading.

What geepherder said.

With the speaker wire disconnected from the amp there should be (in theory) infinite impedance to ground. A finite impedance is a problem. 0.1  ohms = problem, 4 ohms = problem, 100 ohms = problem, ect.

Oh, if you have any passive x-overs you will need to do the same check between those and the individual speakers.