Hi everyone,

I am a new member, but 6-month lurker, and have found the help on this forum among both hobbyists and experts to be amazing.
I have done a lot of work to my 1998 XK8 4.0 coupe (Kitty), such as:

New control arms
New radiator
New brake lines (paid a mechanic to do these)
New parking brake cabling
New timing chains and tensioners
New radiator hoses
New brakes/rotors
New water pump/ thermostat
New serpentine belt
New belt tensioner
Repaired the ABS Module (solder fix)

I currently have one big issue left with Kitty, that I'm hoping that someone can shed light on.
After Kitty has been driven for about 30 minutes and has had the chance for all components to come to running temps, if you shut it off and try to start it after about 20 minutes, I get a traction control/ABS code and she will not start.
If I open the hood for 2 minutes and allow some heat to dissipate, she starts right up.
If I try to start it after shutting it down, but wait less than 15 minutes, it will start just fine.
I have replaced the coolant temp sensor just in case (it was cheap and I was changing thermostat, hoses and radiator anyway)

The car has had this issue since I bought it about a year ago, but only happens if the temp outside is warmer (say 80+ F).
Reading on online it seems that the cars cooling fans are meant to run after shutting off if it detects that the engine is too warm.
That never happens on mine and in theory would provide the same benefit as my opening the hood.

The cooling fans work as appropriately otherwise (slow and high speed works, A/C kicks fans on, as well as when getting warmer while running).
But once the key is off, the fans do not run.

I would just live with the issue, but I am fixing this car up for my daughter.
She found the car for $1500, and I'm doing the repairs myself (so going the expensive route of taking to dealer to explore is not really an option, plus that's not the fun of it)

Does anyone know which sensors are involved in determining whether to turn the fan on after shutdown?
Or if you have any other insight, I would be very grateful.
As Dad, I just can't let her drive a car that may leave her stranded somewhere for any amount of time.

Thanks to you all ahead of time for the help and hopefully I can return the favor on some of the issues on which I have worked.
Also, if you need me to gather any more info, just ask.
I hate sensor issues, I love mechanical issues.

 

KittyVet

Lovely that you’re doing this for both her and the car. She’s very lucky.... both her and the car.

Probably the relay. Check out this old thread

https://www.jaguarforums.com/forum/x...ensors-158097/

 

At that point, you would have to check the codes with a Jaguar/Land Rover reader. This will give you specific codes to search by.

 

I have been able to retrieve codes that show for the Climate Control Module.
The codes are:
B1858 - Refrigerant charge low -or- Refrigerant dual pressure switch circuit open circuit, high resistance or short circuit to B+ voltage -or - High engine temperature in high ambient temperature
B1948 - Signal circuit between instrument pack and A/CCM open circuit, high resistance or short circuit to B+ voltage

Not sure quite what to look for on these.
The "high engine temperature in high ambient temperature" sounds like my issue since everything works once I open the hood for a few minutes. But it sounds like an effect and not the cause.
Does anyone know if these codes would indicate why the fans are not coming on after shutting the hot car off.
Checked coolant temp (208F) and ambient temp (93F) through the scantool, so the system is getting the right values.

Thanks in advance as I am at a loss, and can't find good information on the internet for this.

 

Not sure if this helps, but I can't recall my fans ever running after I turn the car off.
Not long after I bought the car suddenly the fans would run after I shut the car off. I took it to the dealer (under warranty) and they changed the thermostat and that stopped the fans running with the car turned off. I guess the failed (open) thermostat would allow hot coolant from the engine to keep circulating to the radiator, thereby keeping the radiator from cooling off. Anyway, it's been fine for the last dozen years.

 

To my knowledge, the fans run after the engine is shut off only if the coolant temp is high. It then runs for a fixed amount of time after that. In other words, under normal circumstances, the fans do not run after the engine shut off.

Taking the ABS error as a hint, maybe locate any relay involved, and swap it with another to a less important function. I believe most of these brown relays are the same, and can be swapped out.

Best of luck, keep us posted.

 

My fans go off when I turn the car off. There was another thread about this somewhere about heat soak. A lot of times I will open the hood when I get home. I wish the fans did run after the car was turned off - I've had other cars that did. That would be a useful sticky, if it was figured out. Maybe it's just a matter of unswitched power to the relay or sensor.

 

Considering it’s a consistent 120degF ambient shade temp, here in Bahrain, my cooling system gets a real work out on my daily driver. My fans do stay on for a few minutes after leaving the car.

Still think you’ve a problem with a relay (check my previous post)

 

Found this old thread

https://www.jaguarforums.com/forum/x...cation-214400/

 

+1fans should stay on if coolant temp is above a certain point. Took a short drive in 95 degree weather with ac on - fans stayed on for a few minutes after shut off. Orginal postet note I have a 98 too.

John

 

Replaced the abs module with a rebuilt one, and traction control error is gone. I purchased the autoenginuity scanner which showed the code for abs pump circuit failure. Guess my solder job was not as good as I thought.
Still get error once shutting off car and restarting after 15 - 30 minutes. Error now says transmission fault and engine safe mode. Tried to retrieve error, but when car does not start, the ODB port no longer works (tried 3 different scanners - no connection establishes).
Did find what looks like a sensor plug tucked away beside ABS. Can anyone identify it in the picture ?
it is round, three holes, bayonet mount, and reaches toward center of car in front of a/c evaporator.
As a side note, Climate Control module is not showing any values when checking with autoenginuity scanner (screen shot is from a running car with cold a/c blowing).
Any help to save the last of my mind is appreciated.

 

I'm finally back.
Took kitty to 3 mechanics including the Jaguar dealership.
Finally the 4th mechanic offered some clue.
He says that the issue is not the transmission at all, but instead is an electrical issue in the Instrument Cluster. (but he can't diagnose the Instrument Cluster)
(oh, and the weird wire above was some leftover aftermarket power supply from PO)

Now question is, has anyone seen papers on how to troubleshoot the Instrument Cluster ?
Hate to go in blind.

Thanks in advance, especially since this one issue seems to even have the Jaguar-trained mechanics stumped.

 

Check the TSBs on jagrepair.com for clues. There is a range of VINs with (fixable) bad solder joints crashing the CAN bus. Take the VIN ranges with a grain of salt and check for yourself. The IC is not hard to remove. And yes, take advantage of the IC in your hands to replace the 4 illumination bulbs. The official fix involves re-doing the solder joints at the shop, so it can't be that hard to do.

Best of luck, keep us posted.

 

[QUOTE=JimmyL;2101202]My fans go off when I turn the car off. There was another thread about this somewhere about heat soak. A lot of times I will open the hood when I get home. I wish the fans did run after the car was turned off - I've had other cars that did. That would be a useful sticky, if it was figured out. Maybe it's just a matter of unswitched power to the relay or sensor.[/QUOTE




Hi,Try when turning the car off right away turn the ignition key back on but dont start the car. I found out that mine will fans will keep running .