I recently aquired a stewert warner electric trans temp gauge. I installed it along with a fuel pressure gauge. I put the sender in the tranny cooler line. The fuel pressure gauge works fine but the trany temp gauge just pegs to zero when i turn the car on. Can't seem to find anything wrong with the wiring either. Any ideas?

 

Not exactly sure where your sending unit is, but is it grounded?

 

Well, it is not grounded. The sender has a provision for one wire. I got the idea to try and ground it so what i did was connect a wire to the brass housing to the chassis and hold it there while someone turned on the car. The gauge pegged at its maximum temp so i don't know whats going on there.

The sending unit is in a brass t fitting with barb ends on either end placed inline with the incoming trans cooler line.