I came home tonite with the car and after turning off the motor, the fans continued to run for 20 minutes. I drove the car around the block again and the same happened. I would think it is a fan relay or controller. Where are they located and has anybody else had this problem? I just bought the car two weeks ago.
I finally unplugged the fans so the battery would not run down
.
Any help would be greatly appreciated

 

When my fans were running like that it signaled a bad water pump. Maybe one of the impeller fins busted off (plastic) qnd jammed the line. My mechanic replaced that and the thermostat and its been fine ever since. My engine temp never went over half for a few months and then all the sudden one day it climbed up and i had it towed to his shop.

 

thermostat - seconded....

 

Also verify that both fans are operational

 

I came out this morning and plugged the fans back in after the car sitting all night and the fans both came on instantly. What is telling them to stay on even when the motor is stone cold? That would not be the t-sat would it?

Temp gauge does not climb one bit. I have read on other posts here that the gauge is not very accurate and is merely an idiot gauge.

I will change the thermostat and the water pump. I have also been reading that the motor is merely a ford motor. Is that true? If so will parts interchange such as the water pump and the thermostat? It is a 4.0

 

Neither thermostat nor water pump are going to cause the fans to be on when the ignition is off or when ignition is on, but the engine is cold. Either one of the relays' contacts are welded shut (one of the relays closed will cause both fans to operate in series - at half speed), or they are being provided the signals to turn on.

The signals that drive the Radiator Fan Control Relay Module (RFCRM) come from the ECM - there are two. These are used in combination to select OFF, one fan ON full, both fans in series (both ON half), or both fans ON full. They are controlled by signals generatered by the ECM from information garnered from several systems, most likely the engine coolant temperature sensor, the engine oil temperature sensor, the refrigerant pressure sensor, and the AC module.

Measuring the RFCRM input signals with a multimeter will tell you what's going on. If either of these two signals (the Orange/Green stripe or White/Blue stripe at the RFCRM) are low - close to 0V with ignition on, the ECM is telling the fan or fans to be on.

The RFCRM is front, left side of car by the radiator (adjacent to the LH crush tube, according to the manual) in both left and right hand drive models. It has a black, 8 conductor connector with seven wires (pic from wiring diagram below).

 

Thank you very much. I will check those wires. I cant view your wiring diagram as the moderators say I am too new yet.
I also unplugged the two relays next to the fan (on the left side of the core support)one at a time and the fans did not shut off. I am not sure if they were the fan relays or not.

 

The fan relays are in the one module described above - the Radiator Fan Relay Control module - with 7 wires in an 8 pin plug.

If you're too much a noob here to see the image, you can get the wiring diagram from

http://www.captainjaguarscathouse.co...ec%20Guide.pdf

and the pertinent info is on the top left of figure 7.2, page 51 of the pdf file.

And if the link won't work for you yet, either, just cut and paste this: captainjaguarscathouse.com/Electrical_Guides and find the 1999 XJ8 diagrams.

If you're interested, here's the logic diagram showing what the fans should be doing as a function of the two input signals' voltage levels:

Orange/Green--White/Blue--Left Fan--Right Fan
----0V------------0V--------ON full----OFF
----0V-----------12V--------ON half---ON half (two fans in series)
---12V------------0V--------ON full----ON full (two fans in parallel)
---12V-----------12V--------OFF------OFF

BTW, where are you in CA?