Hey jaguar family. I have a bit of a mystery. I was driving on the highway and noticed that the temp gauge was all the way to the HOT!!. I pulled over and popped the hood but didn't notice signs of over-heating, limp-mode,boiling over reservoir, fan on constantly at high speed. so i cut the car back on and the temp went back to center. with the car running i watched the fan to see if the fan would kick on and a couple min later the fan kicked on. So the fan is cycling on and off like it should. But i did notice awhile back the fan stayed on after i cut the car off, but i had a problem then. But non of that has happen this time...

ANY ONE PLS SHARE YOUR EXPERTISE

 

Don, because the car did not go into limp mode nor the fans kicking on, that is telling me that your temp sensor and all of its associated wiring is fine. Your problem lies between the ECM and the instrument cluster. It may be possible that something flubbed up inside the instrument cluster and that caused the temp gauge to read erroneously. When you turned off the car and then restarted it, you reset the computer that is in the instrument cluster, clearing the problem. I know it sounds goofey, but stranger things have happened.

 

thanks for the response. One more question> it's seems to happen maybe 20 min after i've been driving. What led up to it was a bad battery. This hasn't happen b4. dunno

 

Don, are you sure that your alternator is fine? Our cars are very sensitive to low voltages in the car and if your alternator is not playing right, it can cause random problems like this. What you can do is connect up a multimeter across the battery and watch it for a little bit as the car idles. You should see the battery jump up to around 13.5-14.4 VDC as soon as the car starts, stay there for a little bit and then it will drop down some to the neighborhood of 13.2-13.5 VDC. If you start getting down around 12.6 VDC, then your alternator is not functioning properly. If this is the case, let me know and I will have some other checks for you to do.

 

Gauge or sender getting grounded? I didn't know the X type used the temp gauge sender for the ecu. Is that what your saying Thermo. With a name like that you should know all things hot and cold I know it was bad but I just couldn't stop myself from typing.

 

You have a text book perfect, classic example of a failing thermostat.

The temperature gauge does not tell the actual temperature, it is a massaged signal from the ECU. when the thermostat gets slow to open the gauge sensor temp rises VERY slowly. the computer does not move the posisiton of the gauge needle until the engine reaches a certain temperature. then it pegs it to cause alarm with the driver.

The fan control module and limp mode are differnet controls with different sensors.

Anyway, I would change the thermostat and everything will probably return to normal.
I would guess you are 4-5 years old, and 150-200 thousand km... (You should include this info in your posts)

 

I get strange things displayed on my instrument cluster whenever I plug my OBD11 tester in to read fault codes. The temp gauge will often read full scale with the over temp red light illuminated. Also get "Gearbox Fault" on the message center, and the RPM reads zero. This all goes back to normal as soon as I unplug the OBD11 tester. The temp. is obviously not really high because usually the engine is not even running. It just shows that you can get very spurious readings on the instrument cluster under certain conditions.
Chris.

 

To Thermo.. i did as you said and ran a VM across the battery terminals.. i got about 14 v on start-up and it dropped to around 3.4 v

To Jimmy.. i will try to replace the thermostat this weekend. I thinking about changing my water pump also since ill have that side pretty much broken down.. whatcha think ?

Also @ Jimmy.. i have 106000 miles on it and it's a 04

 

I would not change the pump until it leaks but then again i am cheap. I am a stickler for preventative maintenance, but some parts just dont have a predictable failure rate. My water pump went at about 210 000 km. You dont have to take it apart to do the thermostat anyway.

 

Thx jimmy.. I'll leave the pump alone until noticable signs of failure.. But i've just puchased the whole upper hose assembly which included the thermostat.. One question. I'm trying to remove the air filter cabinet or what ever the proper name for it is, but can't seem to. i've remove the noticable bolts which is on the top intake manifold but there seems to be another screw or bolt at the bottom that i'm missing. I've searched on line Can you help with this ?

 

Don, yes, our cars have a true temperature gauge. So, the temp sensor have a varying resistance that is relative to the temperature of the engine. This resistance is sent to the ECU which then converts it to a temperature signal. This temp signal gets sent on to the necessary components for control. One of these components is the "limp home" circuitry and also the fan control signal. Since you weren't getting the fans to run or the limp mode, it can be safely assumed you didn't have a true overheat condition. So, this leaves a problem with one of the components for the temp gauge. Since the signal is processed by the instrument cluster to be turned into something that you can see, that doesn't leave a lot of things that it can be.

As for your voltages, I am assuming you meant to say that you got 14 VDC initially and then it fell to 13.4 VDC, not 3.4 VDC. If this is not the case, please let me know.

 

Once the top is off the filter box, the bottom has just a few more screws. They should be all obvious. a couple to the valve cover and then a couple inside that attach the box to the front snorkels. when those screws are out, the box pulls straight up, leaving the retangular part with the snorkels behind in the car. Does that make sense?
You gain most of the space for access to the thermostat by removing the battery box. I had my battery box out today, to do a pre-winter battery cleaning, and terminal cleaning. I checked the battery water level too....

 

Special Thanks too Thermo and Jimmy.. I do believe the problem has been solved .. i don't won't to count my chickens b4 they hatch but i havn't had the problem duplicate its self. I changed the whole upper hose assembly which included the thermostat. Was a bit of a challenge with clearance between the thermostat housing and fan but was able to get it out. I hope this fixed the problem....... plus i have new hoses too..

I really appreciate all of you guys support and concern...