2006 GMC 2500HD brake switch failure

[Guest]

I have already read a couple of the posts on here about this. I am getting plenty of power which I think is my problem. I replaced my alternator thinking that it was sending too much voltage at 19 V to the that battery. The new alternator came with a spec sheet that said it should be putting out 19.6 V. Is there something between the alternator and whatever else to bump down the voltage? I'm getting full 19 V at my taillights. I've been through 14 brake light switches

[carriedi]

try another alternator. While the alternator can charge at higher voltages, the regulator should cap output to 15.5 max. 13.8 to 14.2 should be the average running voltage.

scan the vehicle and see if the scanner shows ignition voltage at 19 volts. If the scanner doesn't see the over charge look for a bad connection or bad ground somewhere. If it does see 19 volts, change the alternator.