Twice in the last couple of weeks, I have returned to may car from shopping or errands and when I started the car. The ABS/Trac unavailable message came on along with restricted performance. I turned the car off and then restarted and everything was fine. What gives?

 

How old is your battery? I have had the same issues/warnings when the battery started to get weak.

 

I had a similar problem but replacing the battery didn't correct it. Then I had the sensor replaced and all is well. Owning a Jaguar is a very steep and expensive learning curve.

 

This is probably one of the most common issues, and it isn't necessarily expensive. There are many threads about solving it, and there are even a couple of FAQs. Just do a search, or go to the FAQ thread (it's a sticky at the top of the XK8 forum).

 

Thanks all. As for the battery, it was replaced last year. Not sure about the sensor issue but I'll check the FAQs.

 

Without scanning all the related modules you can only guess at the problem. The fault(s) will likely show up in the ECM or ABS module but a network fault could cause problems. Get a scan and there will be less guessing.

bob gauff

 

Bob,
Thanks. I'll get it scanned. Funny thing. It happened again yesterday. This is the first time it happened while I was actually driving. The fault came on the moment I plugged my GPS into the cigarette lighter. Weird.

 

Rather than being a funny coincidence, I would bet that plugging in the GPS increased the electrical load on the system, which caused a voltage drop and triggered the fault.

 

Happened again yesterday twice so I took it to the mechanic. Scan showed multiple misfires, all cylinders. Prognosis: electronic component in throttle body needs to be replaced...which means entire throttle body needs to be replaced $$$$!

 

NOOOOOO!!!!!!! Don't spend big bucks on that without trying the cheap stuff first. Check the battery. Take it to an Autozone or Advance Auto Parts and they'll drag this little cart out to your car and load test the battery. It might show normal voltage while just sitting there, but when they put it under load it might show that the battery is bad. Also, check the connections on the battery. Take off the battery leads, clean the terminals with a wire brush and then put the leads back on the battery. Check the ground wire to make sure it is securely attached to the chassis.

Your problem seems to be relatively common judging by the number of times this question is asked here on the forum. And more often than not, the problem is battery related. These cars have very sensitive electrical systems, so it's in your financial interest to make sure the battery is up to snuff before spending big bucks on a throttle body.

 

I'll check it but the battery was replaced less than a year ago.

 

Read this before you purchase a TB http://www.gusglikas.com/AutoRepTB.htm If a TB is necessary then look at reconditioned ones and save a few bucks. Problems have been known to exist without throwing proper codes. As for the ABS / Traction Control You need to check and clean your sensors and sensor plugs first. A repair for a common problem in the ABS module is available http://www.gusglikas.com/images/Auto...e%20Repair.pdf but check your sensors and connections first. If you look you can find a nice post on the sensors and ABS module in the xk8 posts

I do agree to have the battery checked first.

 

Most auto parts places will load test it for free.

 

I'll check the battery today then check out the TB plugs Gus suggested.

 

The other thing that happened when it went into restricted performance was that the engine was missing like crazy. That's why the throttle body diagnosis made sense.

 

Get the battery checked!

 

Couldn't get there today. I'll get to Advance Auto Parts tomorrow and let you know what they say about the battery. Hope that's the problem.

 

Went to Advance Auto and had the charging system checked. Everything was perfect. Back to the TB?

 

That sucks. Gus' advice is your next step.

 

Thanks Reverend Sam. Hey Gus, if it comes to that, where do I find a reconditioned TB?