If the pump fails do you get a MIL or a message on the instrument pack? Just wondering.

 

No, you don't get any sort of warning.
The pump is activated by the intercooler pump relay and there's no feedback wire or other mechanism to verify that the pump is running.
Easiest way to test the pump is to switch the keys to "Ignition ON" and you'll hear it running.
If you want to replace the pump because of failure or as a preventive measure then you should consider replacing it with a higher flow pump from Bosch.
For more info see here: Klick

 

Just 'jump-the-relay' in the relay box in the engine compartment.
You don't even need to turn the key on!
Key on and the pump runs.
Either way.

 

As others said, there's no warning but 25-30 mile down the road your car will get very slow & horrible to drive as the ECU backs the timing off to stop the pistons melting. I found this out when I got my XJR & the fuse had blown for that pump, it's 15amp in the smaller under bonnet fuse box.

 

Thanks all for the info. When I first got the car I wondered what the key on hum was and quickly figured it out. Car has 191k miles. Drove Pensacola to Orlando today and ran great. If what @Hooli described happens can you limp home without damage or should I proactively replace because of mileage?

 

mine blew several fuses & ran like that a over the first few months I had it, doesn't seem to have done any damage. I wouldn't have wanted to do it in hot summer weather though.

 

If the pump is pulling enough amps to pop a fuse then its time to replace. All the XJR's I've owned have all ran, even rusty looking things still work. But if there's been a mix of coolant (orange to green) or a 'stop leak' water pump/head gasket additive put in, then I'd been flushing the system and adding fresh coolant before changing the pump. Check what the pump draws before and after, if it's still high, time to change. To the Bosch 050 updated version.

 

It behaved for several years after the 3rd fuse went in. So I think it'd blown a long time before & was just sticky.

As it happens it's getting an uprated one next month when a bigger bottom pulley goes on as well as a complete timing chain job.