the speedo works fine up till 40mph , then it quits and the check engine light comes on

replaced the VSS no change , once I am below 40 MPH speedo works fine again

 

I just started having a similar problem with my '99 WG and it's why I just logged on. I was riding and when I pulled away from a stop light, I noticed my spedo was not working, the odometer was off and my check engine light was on. When I let off the throttle and hit the brakes to pull over, it went back to normal until I throttled again and it went haywire again. I ain't got a clue yet but I'm gonna check some connections because it happened right after I hit some bumps. But if you figure it out, let me know.