Ever since we bought the car, after we turn it off and get out there is always a humming sound (sounds like a mosquito to me) but soon after we turn the car off it will quit. I always thought it was the PS fan under there.

However, we just got married last week and took her Mini down to Panama City for our honeymoon and as usual we get to the hotel and park. The car is still doing its humming which was nothing unusual (so I thought) and we go to our room and get settled before we go back out.

We fast forward about 3hrs and we go to the car and the battery is dead. Now this is why I dont like to travel without my truck. Ive got everything I need in my truck and in a Mini and on a trip, well, you just cant bring enough "just in case" things. BUT, I do keep cables so we gotta jump and as soon as I touched the cables I heard that humming sound. So I figured it was the PS pump fan but without tools there wasnt too much i could do so where ever we went for our entire week down there I had to pop the hood and disconnect the battery. That was the only temp solution I could come up with given the tools I had to work with.

Fast forwarding to when we are back home. So I lift the Mini and disconnect the PS pump fan and reconnect the battery and thats not it. So I remove it out of the way and it seems the humming noise is the PS pump itself. I placed my hands on the pump and when she touched the battery cable the pump would jump just a bit from it turning on. So Im sure thats what it is. Now the pump obviously works because we have PS in the car but its just that it wont turn off.

So what controls this pump? Is there a relay that could be bad somewhere?

 

There a several threads with this problem......Sometimes the wiring harness near the pump rubs and chaifs, then goes bad, sometimes pump itself.....often the circirit board that controls it craps out, or gets shorted from the carbon from the brushes in the motor......either way, a reman/new pump or a replacement harness is the answer (from what I have read-there is a thread by a guy that replaced his own brushes, blew off/cleaned the controller BEFORE it failed). Be sure to use CHS 11 fluid when you do the reinstall...it is very different from std PS/tranny fluid.
Good luck!