Hi, my 1990 LS 400 is overheating. It spikes in temp. When idling but cools down when going higher speeds. The fans don't appear to be activating. I read you can test this several ways, but am no machanic and don't speak car well.

I'd rather not burn cash on a machanic if ai can do this on my own. My neighbor mentioned attaching a hot line from the battery to the fans so they run all the time, requiring me to disconnect them after driving. Any advice or superior knowledge is much appreciated, thanks

 

An important sidenote I should mention is I was changing the alternator and lost a lot of coolant. I have been adding more steadily, it possible it hasn't quite filled all the way yet.

 

Regardless, I believe the fans should activate. That's all I've got.
Thanks

 

Is the coolant reservoir full?

 

Yes, coolant is full

 

We're good, it was my coolant. Thank you, I learned how to bypass the fan reley. Cool and important facts. Thanks