I thought I would share my recent experiences in hopes it could help others in the future. Last week I noticed the temp gauge starting to creep up. I pulled over and checked under the hood. Everything seemed fine. No leaks or bursts, coolant level was good...could not figure it out. I let it cool down for half an hour, started her up and made my way home.

Everything is fine for the next three days. Then it happens again. Only this time it won't cool down enough for me to make it home. I had to flatbed it home much to mine and my wallet's chagrin.

The next morning, I remove and test the thermostat by dunking it in a pot of boiling water. I visually confirmed that it was opening at the correct temperature. Next, I remove and inspect the water pump. No leaks, gasket is fine, impeller is fine, but I replace it anyway for peace of mind.

At that moment it occurs to me that I didn't remember hearing the fan at all when the engine was overheating. The fan should turn on automatically whenever the AC is on. So I turn the AC on and the fan doesn't kick on. So I replaced the F14 and F35 fuses, and still no joy. I crawl underneath and disconnect the fan electrical connectors, clean them and reconnect. No joy. Then I disconnect/reconnect the coolant temperature sensor. Bam! The fan is working again. At this time I also notice that the plastic connector on the sensor is loose, meaning you can basically spin it around. I run down to the Jag dealership down the street and get a new one, throw it in, and the fan is working properly again. My guess is that the sensor was beginning to fail, leading to intermittent operation of the fan. I will continue to monitor the fan over the next few days and will report back if this was indeed the cause.

 

That was good trouble shooting!

I would not have thought to check the temperature sensor connection and probably would have replaced the fan and module assembly for no reason.
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Well so much for that idea. The fan stopped working again. I guess the only thing left is the fan itself. I believe there's a module and a motor, or are they the same thing? I'm on my phone right now so I can't look up part numbers or anything like that. Does the whole fan assembly have to be replaced or just the module or motor? Any tips before I begin my research tomorrow would be helpful. Thanks.

 

So I leave the car alone overnight and decide to fool around to see if the fan motor can be removed without removing the entire assembly (it cannot, as it is attached to the fan blades on the other side of the shroud). There are three bolts attaching the motor to the shroud. After discovering it could not be removed, I began to retighten them. The end of my wrench came into contact with the aluminum support bar on the subframe while the socket was on the bolt. There was a tiny spark off the end of my wrench and the fan turned on its own ever so slightly. After I fully tightened all the bolts, I could not duplicate this oddity. I start the car and the fan is working again. But this is the pattern: it works for a few days, then fails, works for a few days, fails. Could that spark signify some sort of electrical short in the motor?

 

Poor ground?

 

Interesting thought. I wonder how I could test this further. Or should I just bite the bullet and order a new motor.

 

Hi XJ8JR,

I would suggest you check the schematics in the Electrical Guide to see if there should be any voltage on the fan mounting bolts. My guess would be that there is always battery power at either the fan module or motor, but that there shouldn't be voltage on the mounting bolts. You might test the voltage between the mounting bolts and a good ground point.

You can download the 2005 X350 Electrical Guide here:

http://www.jagrepair.com/images/Elec...al%20Guide.pdf

The schematics will also tell you where the fans are grounded. I won't be surprised if it's one of the ground studs behind the headlamps. Note that the torque spec for the nuts on the aluminum ground studs is just 6.5 ft. lbs., barely more than hand tight. Several members have accidentally snapped off a ground stud by overtightening the nut.

Have you tried powering the fan motor directly with 12V? You'll have to check the schematics to know exactly which wires to apply the 12V to so you don't fry the module. Let us know if you need any help figuring out the schematics - they can be confusing if you don't have much experience with them.

Cheers,

Don

 

The fan module is separate, it's under the core support (look up in front of the alternator), you remove the front lower air dam to access it.

The a/c operation should have triggered the fan regardless of the engine temperature. The module receives a signal from the PCM telling it how fast to run the fan based on various temperature and pressure inputs.

Could well be the fan motor itself, but definitely worth checking the module before throwing money at it. If your fan motor has voltage when the a/c is on, but the fan is not running, I'd bet on the motor.

 

I'm pretty sure the fan module is part of the motor assembly and not a separate item.

 

I don't believe they changed it between model years. I know for a fact that mine is under the core support, almost directly below the engine fuse box. There should only be two heavy gauge wires feeding the fan motor, while the module has a separate connector from which it receives data from the PCM.

 

Take a look here
https://www.jaguarforums.com/forum/x...an-mod-104790/

I posted full details on how to make the fan go full blast. We use this mod to cool down the intercoolers prior to a drag run

If you replicate the jumper wire in the second pic the fans will be on full. If they don't come on you either have a power supply issue or a bad fan/module
The fan/module are one part so if this is your issue you need a new fan assembly

Cheers
34by151

 

Either the forum is glitching today or I'm having Javascript issues because I can't see the vehicle info in the signatures of 34by151 or mhamilton, and I have to go back to post #1 to see that XJ8JR's car is a 2005, so I can't tell if we're comparing apples to apples.

According to the schematic Michael posted (which matches the one in the 2004 Electrical Guide), the Cooling Fan Module has two electrical connectors, neither of which connects to the Fan Motor, which is shown hardwired to the Module. The 2004 EG shows two 2-conductor connectors to the Fan Module, but the 2008 EG shows one 4-conductor connector. And it's interesting to note that both wires to the Fan Motor are labeled as outputs in the Fan Module, so the motor must be driven by a PWM signal to vary its speed.

Checking the EPC for a Fan Module, I couldn't find one listed separately. Only the Cooling Fan is shown, but it has two electrical connectors on its harness pigtail:




So the question is, what year cars are we comparing here, and is it possible that on some years the Fan Module is a discreet component?

Cheers,

Don

 

Don,
The Module and Fan are one part. You cant replace them separately
It is mounted into the fan shroud and is not shown in the picture posted above


The Larger pug has the power for the fan (via the module)
The Smaller one has the power for the module and the PWM ecu signal


Cheers
34by151

 

Right. That's what I gathered from the schematics and parts catalog. So what is the separate component Michael understood to be his fan module?

 

If I am incorrect about the module, I apologize. I've had my fan out of the car to clean, I have a distinct memory of the module being separate. Maybe repairs on this car are starting to run together...

 

Oh, I've definately had that feeling. :-(

 

I sourced a low mileage fan and motor from a local junkyard and swapped it in. I saved a few bucks by replacing only the fan and motor, not the entire housing assembly. So far so good, and the new fan seems to be much quieter than the old one, making me think that the old motor was indeed giving up the ghost. Only time will tell.