2000 Chevy Astro van’s fuel gauge problems

“My 2000 Chevy Astro van’s fuel gauge always reads full when I turn the van on. When I just use turn the key half a turn so the battery turns on the interior the gauge reads low fuel. Also my interior dome light does not go on when doors are open. It works when the light switch is turned on. I noticed that the previous owner had wire running to the rear of the van for some lights on a trailer. Could this be the problem? Where do I start looking? Thanks”

Odds are you’ve got more than one problem there. The fuel gauge can be a bad sending unit, a bad dash unit, a problem in the wiring, OR a problem in the small computer that runs the dash (called body control modules OR General Electrical Modules.) Since your gauge reads full when the vehicle is running, but empty when you just have the key on and the engine not running, I doubt that it’s the sending unit in the tank. It would read the same as long as power exists in the circuit, whether the engine was running or not. I would assume you have a problem in your dash, in the dash wiring, OR in the general electrical module in the dash. Tracing it down will be no fun, so why not just fill your van up and reset the trip odometer and then just fill it up again when you’ve gone your usual refill distance (say every 250 miles.) That won’t cost you anything. As for the dome light, you’ve probably got a short in the wiring or switches that go to the doors, as the light works when you turn its switch on. So check all the doors and back hatch to see if you’re getting power to the switches and check the switches to see if they work when they’re turned on and off. Good Luck.