12 lighting problem

[ALAG321]

I am refurbishing a 1988 TT and cannot figure out what is wrong with the 12v lights. I checked the battery, and it is fine. I ran a long jumper wire from the ground on the battery to my test light and I have power at the socket in the 12v light, but the bulb will not come on in any of the 12v fixtures. I even tried a new bulb to be sure, but nothing. This has me thinking I have a ground problem, but, then again, the water pump functions normally. There is only one ground wire hooked to the battery, so it has to be the same ground feeding the lights, right? Also, when I touch the test light to either the end of the bulb in the fixture, or the side casing, my test light comes on. I thought the side casing of the bulb is for the ground, but I'm not sure. Any suggestions?

[ALAG321]

I am refurbishing a 1988 TT and cannot figure out what is wrong with the 12v lights. I checked the battery, and it is fine. I ran a long jumper wire from the ground on the battery to my test light and I have power at the socket in the 12v light, but the bulb will not come on in any of the 12v fixtures. I even tried a new bulb to be sure, but nothing. This has me thinking I have a ground problem, but, then again, the water pump functions normally. There is only one ground wire hooked to the battery, so it has to be the same ground feeding the lights, right? Also, when I touch the test light to either the end of the bulb in the fixture, or the side casing, my test light comes on. I thought the side casing of the bulb is for the ground, but I'm not sure. Any suggestions?

[falconman]

Follow the ground from the battery post. It has to be connected to all the fixture wires somewhere. For my trailer it leaves the battery negative post and goes to the frame where it meets several other large ground wires. These wires then disappear into a enclosure where they are tied into other smaller ground wires. Also check to the rear of the 12 volt fuse panel. There may be some ground connections nearby.

[ALAG321]

I finally found the problem. The ground wires are connected in near the converter and whoever owned it before me had them taped with electrical tape to the main ground for the trailer. The main ground wire had come out of the electrical tape. I put them all back together with a wire nut and all is working fine. Thanks for the input!