I took my 98 XJ8 68,000 original miles to a local mechanic for a front end wheel bearing replacement and when I got the car back it has been lighting up like a christmas tree. I am receiving the following lights ABS, Traction Control, Stability Control.

To give you a little more history the cars has had the battery light not charging message going on for several years. So yesterday it was scanned for codes and I was told the alternator was bad. The mechanic's believe the spikes in the alternator output something like 16-18 volts are causing this to trip the computer. Is it possible? I find that kind of weird that all of a sudden after years of the car being driven with the battery light on, it is now the problem for these other error messages right after the repair was done....

I am sceptical and uncertain as I have had the car stall a couple times when changing gears from say going to "Park" to Reverse" or vis versa "Drive" to "Park" or when creeping to a stop light.

Before a ton of $$$money$$$ is spent on the alternator, it would be great to have some other experienced members input and opinions on this matter.
Thank you very much in advance.

 

Check to make sure he plugged the speed sensor back in, or that he didn't damage it.

 

After the first sentence, that was my conclusion too. I accidentally cut a speed sensor line when doing a brake job on another car, but with your same results.

On the other hand, voltage is a menace on these cars. Personally, I'd start with checking the speed sensor, but definitely address the alternator if it's putting out wrong voltages.

PS: Have your local Autozone or other autoparts store do a free alternator test for a second opinion if you are questioning their alternator diagnosis.

 

Probably cable as noted above. If it is the cable, buy it from Jag and install yourself, no brainer & save the labor. But I'd go ahead and pull the sensor and give it a cleaning. Soapy water and a brush. Try to keep water out of connection area, or at least let it dry out good beore you reinstall. I had been getting intermittent ABS/Stability Control faults, found a thread by Reverend Sam, on how to clean sensors. Slam dunk, cured my problem at least.