i have an 87 S4 TII and my stock temp gauge is not functioning
I checked the connection under the hood and it isn't rusted and seems fine
Where else can i check to fix the problem?

 

Ground the wire off of the sending unit. Have someone watch the gauge. If it moves, then your gauge is fine and the sender is toast. If the gauge does not move then it's toast. I'm having the same problem right now. I just said screw it and bought an aftermarket gauge.

 

Years ago, I had a similar problem with my S4. I ended up soldering the connections on the driver side kick panel. That cured it.

 

where is the sending unit?

and wackyracer which connections did you solder?

 

the sender is right below the oil filter. I believe the wire is yellow stripped wire. I cant remember exactly. the box im referring to is located behind the driver side kick panel. If Im not mistaken, there is a thread on this in the 2nd gen section - FAQ.