60hp Mercury 4 stroke 2013 High pitched squeals

by Steve Jones
(Lindstrom, Minnesota)

I get a high pitched squealing sound when I turn on the motor on my 20 foot Sunchaser pontoon. Motor is a 60hp Mercury 4 stroke 2013 model. Has run and started perfect up until two days ago. Found out the horn wasn't working either so thought it might be an alarm for the horn. We bought the pontoon and motor used so do not have an owners manual to tell if there are alarms in the electrical or not. We did get the squeal sound to stop when the boat is still up on the lift but starts up the minute we lower the boat to the water level. Any ideas or thoughts are welcome at this point ? Thanks