Today my wife came home, shut the car off and the top right cooling fan won't shut off. I waited to see if it would shut off on its own and finally pulled the fuse, after it ran for more than 30 minutes. I've read a few things can cause this. And I've searched the forums and googled it, but cannot find info on where the relay is located? Any input will be greatly appreciated.

 

Hi tempests,

A cooling fan that will not shut off has been associated with the coolant thermostat being stuck closed. Since conducting a definitive test on your old thermostat requires removing it, you may as well have a new one on hand and replace it preemptively since they're inexpensive. However, if you still have the original plastic thermostat housing/tower, you may want to also consider upgrading to an aluminum housing/tower.

It is also possible that the Radiator Fan Control Relay Module is malfunctioning. To locate the module, raise the front end of the vehicle on ramps or jack stands and follow the fan electrical harness to the the crush tube near the lower left corner of the radiator. The module is a long black plastic rectangle shown in the photo below. Try tapping on it with the handle of a screwdriver while the fan is running after shutdown to see if the relay will open and shut off the fan.





Here's the schematic:


You can see that if the middle relay sticks closed, the right hand fan will continue to be connected to battery power [73]. You can download the Electrical Guide here:

Jaguar X308 Electrical Guide 2001

Cheers,

Don

 

I tested the thermostat, temp sensor and harness, all seem to be functioning properly. And testing the relay shows it's stuck. So I think I narrowed it down to the relay. I found a new one for about $80.00 and used for $24.00.
I also found a Dual Electric Cooling Fan Wire Harness Kit, 185 On, 165 Off Thermostat 40 to 50 amp relay for $30.00 with free shipping on Amazon. Would something like this be better all around? It comes with 85 Degree Thermostat Switch, 1 Relay Wire Harness, 1 3/8" NPT Thread-In Probe, 2 Ring Terminals, 2 Fan Pigtail Connectors, 1 Fuse Holder, 3/8" to 1/2" Adapter, 30 & 40 amp Fuses. It is definitely cheaper than the relay.

 

I don't think you want to fit the aftermarket system because it would probably lead to constant Diagnostic Trouble Codes (DTCs) being triggered related to the cooling fan drive circuit (P1136), fan slow circuit malfunction (P0480), fan fast circuit malfunction (P0482), etc. It might further cause other confusion for the Engine Control Module (ECM), which manages fan operation by way of the Radiator Fan Control Relay Module, and might therefore trigger other DTCs or lead to improper fueling or ignition timing as the ECM attempted to correct for what it interpreted as fan malfunction. Also, these codes will likely cause the vehicle to fail emissions/smog testing if you live in an area where that is a prerequisite for renewing your license plates/tags.

Your simplest and best bet is to replace the original fan control module with a new or working used part.

Cheers,

Don

 

It is not easy to convert the Jag cooling fans operation using a universal kit. The original (triple) relay is controlled by the engine ECU and the fans have two modes: lower speed up to certain engine temp and full speed above it. The fans are also triggered by the AC (via the engine ECU) - low speed for normal AC operation and full speed in the event the refrigerant pressure (due to heat) exceeds certain upper limit. The two speeds of the fans are achieved by the triple relay switching the fans to run in series (low) and in parallel (full). If you disconnect the original relay and install the universal kit, you will lose the fan control by the AC (unless the universal kit has this provision) and also, the absence of the original fan relay will probably cause fault codes and maybe even throw the engine into restricted performance.

I suggest you open up the original triple relay (easy) and inspect the relays. The problem may not be there. In any case, it is probably the best to just buy a used Jag relay for diagnostics (and also keep it as spare in the case you find the original one to actually be good).

 

@Don B Thank you. I'm going to replace the module. I ordered it online because there was quite a difference for a new one between my Jag dealer and a Jag dealer online. ($120 vs. $79). It should be here by Saturday. Again Thank You

 

I wanted to do a follow up, in case this pertains to any other members having similar issues.
Following @Don B instructions and links, I tested the thermostat, temperature sensor and water level. All tested good.
Then I checked the Radiator Fan Control Relay Module and it was bad, so I replaced it. The problem is solved. The top right fan that would not shut off, even with the engine off, now shuts off. And fans are back working properly.
The exact location of the module, for my 2001 Vanden Plas was exactly where @Don B showed it was. I jacked up the car, on the drivers side, removed the gravel guard and could clearly see the module. It was very easy to replace. The connector may be hard to pull off, but a little wiggling should free it up. And don't pull it by the wires, as it could break a wire.
Thanks for all the help.