Speedodometer starts working past 35mph

My speedodometer does not start working until I get to 35 mph. Any ideas why or what I need to check?

Do you also have a constantly-on ABS light and Brake indicator light? If so, for me it was the rear differential speed sensor...about $50 bucks for the part at the Stealership.
Dave

I have purchased a new switch already and waiting for it to arrive in the mail. I thought this might have something to do with it. Thanks.