I drove my xj into the workshop at lunch & hooked her up to the jeep Techconnec just to run her numbers & check for any ecm pcm updates & low & behold what popped up HIGH AMBIENT OR HOT SOAK TEMPERATURES 2000 - 2001 XJ its a software update that lowers the temp threshold used to determine when the engine fans are turned on , Cooling fans will cycle more often .
Service Bulletin 18-031-03 18-039-03
Ran the PCM update & my thermos used to come on at 104 c to 105 c now they come on at about 98c or by the temp gage a needle width before 100c & thats where it stays , im pretty happy with that , but i have also just fully replaced all the cooling system & removed the AC gear so i have greater air flow through the front so it may vary a little from Jeep TO Jeep
PCM update & re-program is for 4.0 ltr Auto's only
Top work there Rodger , cant wait to read the followups & sorry for the little Hijack but i thinkk it may also help the update xjer's