dome light question/electrical

[1979C20]

Okay, so my friend has an 83 c10 originally a 305/700r4, now a 350. He asked me to help him with his.sldome light and I cant trace the problem. He said one day he opened his door and the overhead light didnt come on. But his friend opened the passenger door some day after and it came on, but now it doesnt work at all. Neither door, or the dimmer switch turns on the light. He bought a new bulb, and I even tried my bulb out of my truck and it still didnt work. Im not sure which fuses are which? I checked tl/courtesy, horn dm, and a couple others and the ones I checked were all good. And I made sure the plug behind the driver side seatbelt is stillnplugged in, but all I did was look at it. Where should I check next? Also, he said some mexicans syphoned all of his gas and ever since, his fuel gauge reads wrong. He says 1/2 tank is empty now. So im wondering if a ground is causing both issues.

[bake315]

Okay, so my friend has an 83 c10 originally a 305/700r4, now a 350. He asked me to help him with his.sldome light and I cant trace the problem. He said one day he opened his door and the overhead light didnt come on. But his friend opened the passenger door some day after and it came on, but now it doesnt work at all. Neither door, or the dimmer switch turns on the light. He bought a new bulb, and I even tried my bulb out of my truck and it still didnt work. Im not sure which fuses are which? I checked tl/courtesy, horn dm, and a couple others and the ones I checked were all good. And I made sure the plug behind the driver side seatbelt is stillnplugged in, but all I did was look at it. Where should I check next? Also, he said some mexicans syphoned all of his gas and ever since, his fuel gauge reads wrong. He says 1/2 tank is empty now. So im wondering if a ground is causing both issues.

Hmmm, not certain about the dome light - that's a fairly simple circuit - maybe pull and check the door switches to make certain they're functioning right.

Sounds like whatever hose or tubing the guys used to siphon the gas, they jammed it down in there so far they damaged the sending unit - the float may only be able to travel so far up/down because of being bent.  Prolly looking at a new sending unit at least.

[txchainsawgogi]

Darn those mexicans.

[bake315]

He says 1/2 tank is empty now.

Or..... maybe it's half full?

[big bear]

lol

[bake74]

     You need to pull the dome light itself out and see if it has a ground wire, or it is using the truck cab as a gound.  Then make sure it is clean and grounded properly.

[1979C20]

Okay, ill also grab my multimeter and check voltage. Thanks everyone

[DnStClr]

Here's the wiring schematic link you need to check for 12volts dc with your meter. it's pretty common for the wire to be damaged at the door switches. Click on the schematic to increase its size. There are two pages.
http://forum.73-87chevytrucks.com/smforum/index.php?topic=11766.0