I don't have that model but I have some suggestions. First under menu > settings > system > GPS Mode > Off If this doesn't work then Check GSC 10 magnet alignment and probe distance. Probe 1/8 " away and magnet centered at end of probe. Push GSC 10 reset button it should flash the first 60 revs. Adjust until it does. It this still doesn't work find speed sensor on/off menu item and turn it on again. This will pair the device again. If all fails call Garmin they'll help troubleshoot. I've adjusted several and usually the cable ties aren't tight enough holding the GSC 10 in place. They have to really be tight.