Speedometer jumping

I think more often than not, the gauges themselves have a tendency to short or the tiny plastic gears strip. The last vehicle I had with a gauge issue was the stepper motor. when I would shut the car off, the voltage that was supposed to tell the gauge to hit ZERO, would cause it to jump up instead of resetting down. So every time I shut the car off or turned the key back on, it would jump about 25% of the way up until it it hit the end of the gauge threshold. I was able to pull my instrument cluster and somehow put all the little pieces back together and it was fine after that. This was not on my caravan so you'll want to do some investigating on youtube for gauge cluster removal.

Turn the key and all the montiors go crazy and wiper go crazy too what can I do

I would try the cheapest and easiest method first, IF you grand caravan has the same setup as my 2005. With key off, push in the trip odometer reset on the face of the cluster, and hold down for about 10 seconds. Gauges should go through a reset/recalibration procedure, which lasts for a minute or so. Sometimes thats all it needs.