Originally posted by fangthorpe
My '92 30' has several of the idiot lights in the dash: specifically - low fuel, low wash and low coolant - that come on and off randomly and with no reason. I actually disconnected the low coolant sender and filled wash water and fuel several times and lights behave the same. They don't flicker, like a cracked circuit board, or come on briefly, they come on for 1/2 hour or so and then go out again. Doesn't seem to be night/day specific, temperature specific or have anything to do with rough roads. It's also not affected by other idiot lights. High beam light works fine. Oh, and they don't all come on or off at the same time. It's been doing it for several thousand miles, so I guess it's not going away. Clearly something is loose or broken under the dash. Do I really have to take the dash out?
Sounds like a wire shorted inside the dash. If you unhooked the low coolant sensor, the washer sensor, etc. and still have the lights come on while the sensors are unhooked, look for the common wire that goes to all three.
I know all three items ground to light, so the first thing I would check is a ground wire. If they were shorted to ground from the power side, you would be blowing fuses, or your fuel gauge would read F or E when this happens.