Negative from the positive

[XJ4IV]

ok so I have the lights on the top of my rig and I burnt out a fuse.. no bigie right... well I put in a new fuse today and had to replace the switch cause the old one had gotten too hot, this spurred my attention to see WHY.
After poking around with the volt meter I show that the POSITIVE ir reading a ground... like 12.76 volts... which is the same as if I were to hook to a ground.?
so I isolated my light and grounded it and removed the lense and put the negative on my meter right at the connector inside the lamp assembly and still had the same reading... Why? I checked the TWO wires since they were now isolated and they were not grounding out I just SOMEHOW got a negative reading from what SHOULD have been the positive side... this is ODDDDDDD.
I hooked the lights back up and you can tell they are MUCH weaker than they should be and the wire from the switch to the lights was EXTREMELY hot from only being on for 5 minutes. When I origianllty installed this setup about two years ago they worked fine and I used them ALOT while offroad at night
Here is the way I set it up

Positive comes DIRECTLY from battery on a 8AWG wire has a 50Amp fuse
goes across my firewall into the fender then into the door frame, at the top of the door frame I drilled a hole and placed a grommet and siliconed the line and brought the line through my headlinerto my overhead console and is there connected to a rocker switch ( basic one that lights up) the ground goes straight up and is like 8 inches long and ground to the body obviously and then the positive to the lights goes back across the headliner... ABOVE it and I drilled a hole and placed a grommet and siliconed again then about 6 inches from there I put in a connector to where when I remove my roof rack all I do is unplug the lights. From there I have a reduced wire to like 12AWG going across the front of my rack where each light is tapped into this line with a quick connect, The lights are grounded to where they mount on the rack and the rack is grounded to the rear hatch bolts.
I WILL say this when I UNPLUG the wire that comes though the roof I get a negative reading... EVEN when it is unplugged completely... I dont get it!!!
Any guidance is appreciated!
Here is a pic of the wiring on the Rack
http://i221.photobucket.com/albums/dd107/basivey/kdk_0333-1.jpg

[4.3LXJ]

I'm not sure what you are doing here from your description, but if I understand you correctly you are disconnecting the ground and then checking voltage to ground on it? If you do that, you will show the proper amount of voltage. If you didn't, you would have a burned out bulb and no circuit.

Your lights are dim because your wire is hot and hot metal causes resistance. Same principle as the filament in a bulb. Are you running a relay? You should with that much current.

It also sounds like you may not have a good ground. Make sure it is a good clean ground. This could give you funny readings too.

[XJ4IV]

no Not disconnecting the ground I was disconnecting the Positivecould you describe how to wire a relay... I think I might have a simple solution and whats the benefit of a relay?

[4.3LXJ]

A relay is a remote switch that can handle a lot of current. A starter solenoid is a type of relay. The type you need is small and go up to 50 Amps. You might want to run two. That will keep you from having a hot switch. Anyway, here is a pic of a waterproof relay. The others wire the same.

http://i649.photobucket.com/albums/uu215/warriorsuspension/IMG_0488.jpg

Inside they all have some spade connectors with numbers on them.

http://i649.photobucket.com/albums/uu215/warriorsuspension/IMG_0487.jpg

#30 is power in and 87 and 87A are plower out. You want #87 for power to the lights. #85 comes from the light switch and 86 goes to ground.

[4.3LXJ]

A relay is a remote switch that can handle a lot of current. A starter solenoid is a type of relay. The type you need is small and go up to 50 Amps. You might want to run two. That will keep you from having a hot switch. Anyway, here is a pic of a waterproof relay. The others wire the same.

http://i649.photobucket.com/albums/uu215/warriorsuspension/IMG_0488.jpg

Inside they all have some spade connectors with numbers on them.

http://i649.photobucket.com/albums/uu215/warriorsuspension/IMG_0487.jpg

#30 is power in and 87 and 87A are plower out. You want #87 for power to the lights. #85 comes from the light switch and 86 goes to ground.

[XJ4IV]

ok Ill give it a whirl...

[Mudderoy]

Voltage is a measured difference between a ground and a voltage source, or two voltage sources.

If you measure voltage difference between 110 volt line and a 220 line you'll read a voltage difference of 110 volts. Does that mean that the 110 volt line is a ground? No.

You are measuring a voltage difference, you need to make sure that your ground is a ground.

[XJ4IV]

Voltage is a measured difference between a ground and a voltage source, or two voltage sources.

If you measure voltage difference between 110 volt line and a 220 line you'll read a voltage difference of 110 volts. Does that mean that the 110 volt line is a ground? No.

You are measuring a voltage difference, you need to make sure that your ground is a ground.

ok I KNOW this much... when I put the end of the meter... one of these
http://faq.f650.com/FAQs/Photos/ElecPhotos/VoltmeterVolts.jpg
the BLACK one on a ground being ANY metal surface on the vehicle and the positive to a positive line ... like the wire coming directly from the battery
it SHOULD read around 12 volts
WHEN I disconnect the POSITIVE meaning there is NO power coming to the source it shows that the POSITIVE on the lights is actually a negative...
I think I need to re check my wires. I will show you this evening at the show