To resolve my electric fan problem on my '88 4.0, I went to http://www.lunghd.com/Tech_Articles/Cooling/Electric_Fan_Diagnosis.htm
The test results tell me to replace the "fan diode assembly". To me, a schematic might as well be in Chinese. I'm good with pictures but I can't find a picture of what it looks like...The folks at Auto Zone say they've never heard of one. Your help is appreciated.

Thanks for the help..That was the culprit...Now everything's cool..

What I forgot to include is that the Jeep dealer told me the Fan Diode Assembly and the ABS Diode were no longer manufactured. They referred me to the local Pick & Pull. I also found a lotta neat stuff I didn't even know I needed...

Hey I was looking for the fan diode too, but I couldn't find anything under my hood that looked like the picture in this thread. Did you end up finding yours right near the air box or what?

anyone know what that does? is it a relay of some kind or voltage regulator or just a fusable link?