Okay so my car has been throwing engine failsafe mode messages for the past two weeks. Would disappear upon restart and come back randomly. Sometimes quickly other times it might take 80-100 miles. Finally got to try to pull the codes with my AutoEnginuity when I got home today and left it run thinking the code was just clearing when it shut of but again no code at all. What would you focus on looking at first? I hate throwing parts at something without at least a code. I do have a spare reman throttle that I got a few years ago but never put on although I would suspect if it was the TPS I would be getting a code from it. Car runs fine. Thoughts?

 

I suspect it could be the TB, try it and see. It'll require a hard reset and idle.

 

Also be certain the battery is fully charged. That's not likely the problem, but it should be eliminated.

 

I do have a weird issue that is going on with my brake switch that might also be part of the issue. Car sat for a few months and now the brake switch doesn't always turn the lights off. It is almost as if the pedal isn't returning all the way up some times Switch works fine and isn't worn or visably worn. I'm thining of attaching a piece of a match box to it (yeah it is a very small amount that I'm taling about) just to see if that temp. solves both issues. Then going up to a pull a part to see if I can come up with some replacement bits and springs.

 

The (dual) brake switch is a well known issue that can cause the failsafe. I had it happen to me, but it did show a code. I assume you have the autoengenuity with the Jaguar pack? If not it won’t show this code as it is Jaguar specific.

Jeroen

 

I just went through the same thing, it was the brake switch. easy way to tell is to go on freeway and put on cruise control if that dose not work it will brake switch easy enough to change, 10 minuet job jrb53

 

As I said though the switch works fine. The brake lights have simply been staying on sometimes as there is a few mm where the pedal doesn't trip it some times and since there isn't any adjustment it makes little sense to me what the problem is or could be. Literally if you pull up a hair on the pedal everything works fine if the lights have stayed on. Zero evidence of where on the pedal or the switch. Figure I will pull a switch and a pedal box out of the pull apart since the two should be about $10.

 

So I wrapped the round metal switch "bung" with electrical tape 3 times today. Not seeing anything else that is wrong or worn. It seems to now be keeping the failsafe off and the brake lights now go out all the time. Seems quite odd. Might make a perm. fix by putting some plastic dip on it to build it up a few mm.