I have the same problem on my 1998 XK8

Question edited for clarity.
Question moved to model category.

This has to be one of the worst electrical manuals I have come across. Download it and Page 24 refers

https://www.manualsdir.com/manuals/132991/jaguar-xk8.html

Jaguar XK8 forum

https://www.jaguarforums.com/forum/xk8-xkr-x100-17/xk8-xkr-handbook-sets-manuals-1997-2006-faq-67827/

ABS

https://www.google.com/search?q=1998+jaguar+xk8+ABS+fuse

part off the module fixed to the pump modulator assembly on lhs under bonnet. common problem, check pump motor resistance should be low 3ohms or less if ok module may be at fault.somtimes you have to change both
but it normally the motor brushes stuckworn out

When the ABS (Anti Lock Brake System) light is on it means the systems control module has detected a failure and the ABS is disabled, this means you just have regular non ABS brakes. To find out what the fault is requires the ABS control module be scanned with a special tool to see what fault codes show up.

u have to change the wheelbearing the sensor in there u can have it scaned to find out what wheelbearing it is.goodluck

The ABS system should be scanned to check where the problem is, however, the most common problem is in the control unit.

abs modules work very hard. by the age of your car it seems that the abs module is packing up. the abs system has sensors on all four wheels that figures out braking, stability and control of the car when cornering. these do brake down over time and is part of the wear and tear side of things. you don't need to buy a new one. they do overhaul these things for much cheaper. your car magazines should advertize the fixing of these things or contact a scrapyard for a secondahand one. check if the abs sensors are not faulty and replace them. do not go to the agents, they will rip you off. good luck

ASC is short for "automatic stability control" u will need to have the ABS/Traction control system tested by the dealer for a possiable fault code.

Number of possibilities. Most likely culprit is wheel bearings. Have these checked. Big heavy car and wheel bearings do take a hammering on XK and XJ's. Once they go, the wheel speed sensors are out of line with the tracking ring and a fault code is thrown. As the TCS uses the same sensor, this also throws a fault. Next in line is the ABS unit (it's hardly ever the main block, but ECU itself, companies on the net offer rebuilt units. Finally it can be the ABS pump unit - but the fault codes will show if this is the case - or you can pull the pump unit plug out of the ABS unit and see if it has continuity with a multimeter - should be a low number of ohms. 8 times out of 10, it is wheel bearing.

The most likely root cause of the problem has been determined, and its step by step fix is also detailed if you have the skills to do that yourself. See the excellent detailed website posting by Dan Jensen on the Jag-lovers.org site forums.jag-lovers.org under avsn.php?1169101j41 . He describes what goes wrong in the $2800 ABS control electronic board, and that simply re-soldering a few heavy wires to the board will fix the trouble. But it requires some mechanical work to get that module out, and then some more work to saw the plastic case apart to get to that circuit board. - Best regards - MHH

We have the same problem with our BMW. Dealer quoted close to $1500, with a one year parts warranty. Go to Module Masters at www.modulemasters.com.

They show detailed info on how to remove your unit, and will rebuild one for a 2001 XK8 for $150. The unit for our BMW is $300.

I have heard great comments about Module Masters. Well worth a shot!