First, check as many chassis grounds as you can find. Make sure they are tight and clean. Also, check the main ground cable from battery. If its badly corroded, then replace.
Now, is there anything else wrong with the car? Driving issues? Trans holding gears too long? Intermittent loss of power, and overall "tune" issues?
My gps clock is the same,, and I dont think its the gps sensor. Renewing grounds helped alot. I believe its related to the common abs sensor issue in the transfer case. Havent been able to replace mine yet,, but I have gone through everything else.