I recently, started having a overheating issue on my H22 which is in my 92 Si. The fan switch works like it should but it still overheats. So far, I've replaced the thermostat with an Oem unit also, the water pump is a new Oem unit. I also, swapped out the sender unit with a known working one. The problem seems to be more affected when the lights are turned on. I read somewhere it's possible a loose ground but I have no idea which one. Any input is helpful in trying to help me fix this issue.
Thanks.

 

Sure enough! It was the ground! All it needed, it seems, was a new chassis ground to the valve cover.

 

Glad to see you solved your own problem lol

 

You can test for a bad ground by starting the car and testing the voltage of the battery then move the positive lead to the engine and it should be the same.

 

Thanks. I still cant believe it was a stupid ground.

 

A bad ground will not cause the car to overheat unless said ground is affecting the Fan circuit. Your bad ground was likely giving you a false over heat reading....

 

Yep. It was causing the temp gauge to read higher than normal. In fact, the fan was working like it should. But, the gauge was off a bit.