Hi Guys,

It seems there is constant inquiries on this forum regarding the fail-safe mode, and what causes it. I would like to throw out a couple of ideas and see where it goes.

My wife's '99 XJ8 has had intermittent fail-safes over the years, and sometimes constant, then go away. She drives very short distances.

Recently bought a new battery, and today had the alternator checked and all OK. Yet, I have discovered that when driving with the A/C, driving lights and radio on, the XJ will go into fail-safe, but when we do not use the A/C and driving lights, as well as idling the XJ for 15-30 minutes daily there are no fail-safes.

My hypothesis is that the XJ's are very sensitive to voltage and the car can not produce enough sustained voltage when A/C is running like it has to in the Houston area.

Question is, is there a module that would be affected by a small dip in voltage or is there a higher output alternator available for the XJ8?

If we can find that low voltage is the problem, a lot of expensive repairs could be avoided for our members.

At this point I am certain that low voltage is the culprit. All ideas would be appreciated.

Cheers
Ken