Bmw 325ix speedometer fail

[Samthekid]

Hi guys

I just bought a 1987 bmw 325ix. Yesterday I was trying to install a new head unit and I must have shortened out something, because after it I went for a drive and the speedometer stoped working. It worked completely fine until them and after the failed radio install the speedometer wont move.

How can I fix this?
The plug in the diff is fine.

Thanks

[Kershaw]

Pull the cluster and see if the connections are loose. Check the fusebox for blown fuses.