smith GT40 GPS speedo install instructions

I have installed my GPS speedo and as soon as I did the needle jumped to 200 mph and continues to want to move further, and now I cannot find my installation instructions to determine if I wired it correctly. The store I got it from won't be open till monday but was hoping to have my dash finished this weekend, anyone with wiring instructions, thanks.

Howard Jones

Do you have a model number for your speedo ? I have tried to Google "smiths gps speedometer install instruction's" and come up no joy. Are you sure it's a Smiths gauge?
yeah I have googled it too, the company I bought it for is closed this weekend, but from what I understand they supply all the GPS speedo GT40 units