What is circuit diagram of a BMW 318 I- Chassis number WBACA32090AK51714?

What could be the cause of the temperature gauge of BMW 318 I 1800 model fail to display the temperature? Plaese help !What is circuit diagram of a BMW 318 I- Chassis number WBACA32090AK51714?Is it a normal gauge or computer type display? if it is the traditional temp gauge find the sender unit pull the wire off and connect to earth (Gauge will read max) if reads zero gauge fault. All the problems similar to this I have ever had the water temp has been cause and no fault with gauges check the water system first if it is computer type take it to auto electrician after first making sure the water temp is right. Some gauges don't even register below about 60C and if it is cold and your thermostat stuck open the water may not be that hotWhat is circuit diagram of a BMW 318 I- Chassis number WBACA32090AK51714?try your library mine has and online thing where i can get free online diagrams.