Faulty air suspension pump?
 

Just bought a 2000 LeSabre Custom about a week ago and after a few days of driving it, I've noticed a humming sound coming from above the exhaust. At first, I thought it was a bad fuel pump, but I don't think that's right. I took a look under the car and noticed a thin (electrical wire?) running from the suspension to where the noise is coming from. I now think that it might be an air pump to my suspension, but I'm not sure. Can anyone tell me what the problem is and how to go about fixing it?