I have a 1999 Jaguar XK8 convertible with only 48,000 miles…

Hello and welcome to JustAnswer. Sorry to hear you are having this problem with the Jag. I will do all I can to assist.

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The Anti-Lock Brake Control Module on our XK8 works to prevent wheel slip not only when braking but when accelerating and cornering as well.

Any fault code stored in the ABS Module will cause the ABS (Braking), Traction Control (Accelerating) and Stability Control (Cornering) lights to illuminate.

The only way to get a handle as to the nature of the fault is to retrieve the stored code(s) in the ABS Control Module.

Most parts stores offer a free scan of the Engine Control Module when the "Check Engine" light is on, but it requires a more advanced scanner to retrieve the ABS codes.

It is hit or miss as to whether they will offer a free scan (or be so equipped) of the ABS module.

The low engine coolant warning isn't related to the TC/Stability Control/ABS lights.

Have you noticed any coolant leaks on the ground ?

One area I recall that was common on this vehicle was the heater hoses underneath the intake manifold to leak.

In this case the coolant will tend to pool in the intake then evaporate before it hits the ground.

Have you checked the coolant reservoir ?

See attached TSB for its' location.

I hope this helps. Please let me know if you have any questions.