***MAP sensor humming/buzzing, key not in ignition***
Was attempting to remove tranny dipstick today due to it having a crack where bracket is tack welded and having leakage where short tube goes in tranny (finish working on this tomorrow, POS). While I was under the hood I noticed a very low buzzing or humming noise. Thought it may have been GPR so listened close but that wasn't it. Finally found the noise coming from MAP sensor. I find it weird because the key is not in the ignition and if I move some of the wires connected to it the pitch changes or quits. Is my sensor going bad or is the connections to sensor not as conductive as they use to be? Should it make a noise with out the key in ignition? It's a early '99 by the way.