I just looked for the Dark Blue / Pink wire (DB/PK) in my harness and it's not there. Next weekend, I'll pull the connector, add a lead to #31, re-attach, and test.
I looked up the relay and connector for the XJ. The fan control relay on the XJ is the horn relay on the YJ.
One good thing has come of all this so far. I found two loose connectors on my harness by the map sensor. I found out one is for a hood light (didn't know it was an option) and the other was a TCC relay which I guess is for locking the torque converter on a A/T, but I'm going to tap my fan relay on it's white/yellow switched iginition
Saves a few extra feet of wire.