1997 Vauxhall Tigra

Hi guys

i have a vauxhall tigra and the speedometer isnt working. It works sometimes and I was hoping if you could tell me where the wiring is connected under the bonnet. I recently went to a mechanic and was told there was some dodgy wiring to connect the speedometer. Can you show me a diagram of where it will be under the bonnet and how it is to be connected.

ps. I know its not the sensor, the mechanic showed me the wiring done under the bonnet: need to know how it looks so I can identify it thanks.

also, my car starts to jerk forward sometimes when im driving, it also has an oil leak. Are they related