Hi all 2000 xj8 I keep getting failsafe engine mode coming up on dash light there are no codes stored or pending. the car run great no problems apart from restricted light which will come on after 2-3 miles I am at a loss what to do next. don't want to start changing things till I know what to fix any ideas thanks jrb53

 

Sounds like possibly a small vacuum leak or a failing sensor. My first thing to check is the filter and the MAF. Then I would check the throttle body for varnish deposits. I say start with these because they are somewhat easy to check and quick to clean and function together.
I had a similar issue when I first got mine in '04. Found it to be a poor design on the SC gasket and it was sucking it in cause excess air to get in. Went down to Jag and got the upgraded seal and plate, no issues since. I know yours isn't SC'd but the possible vacuum leak is my point.

 

In my earlier post I had put as a Title restricted performance .I must of had a Senior moment as I had Failsafe engine mode anyway after checking through old posts on Forum. checked Failsafe mode it told me to look at brake pedal switch as I found out I had no cruise control replaced switch all is well again thanks to forum back on the road again jrb53

 

Hi jrb53,

Thank you for updating us with the resolution of your issue. This will be very helpful to other members.

I merged your latest post into your original thread and retitled the combined thread accordingly.

Cheers,

Don

 

You replaced the cruise control switch (the one by the "S" mode button) and that solved your problem? I never heard that one before.

 

No, he replaced the brake pedal switch: which also cuts off the cruise control.

 

Cheers for this old thread chaps. I found it on google when looking for the same fault on my XJR, I've been out tonight with the cruise control turned off & the 'engine failsafe mode' warning doesn't appear so it looks like I've got the same issue.

I'll take a look at the brakelight switch at the weekend to see if it looks like I can open it to clean it, then probably order a new one anyway when I break it trying to do that.

 

Apparently the micro switches can be sourced if cleaning dosen’t work

This is the switch

 

Excellent. I've ordered a second hand switch, after seeing the prices of a new one, so my plan is to source a couple of microswitches & fix the original as a spare.

 

If you get a part # for micro switch please post it

 

Just buy the X308 brake switch and swap the mount bracket and longer wire connector.

I melt the solder and transfer the wires/connector to the sedan switch, then mount it on the XK bracket.

STANDARD MOTOR PRODUCTS SLS504

Rock Auto for $85.

 

I think this would be a cheaper option.

 

Those look wrong, it's a 3-pin microswitch originally fitted.

 

True, I’ve just been out to the garage and Jaguar used a NC/NO switch so that one would not be compatible. Still there must be something on their web site that would be suitable.

 

Looking at the diagrams, it appears that the brake light microswitch is NO and the cruise control deactivate one is NC. Otherwise, only two of the three pins of the original microswitches are used - NO section of one and NC section of the other.

 

Omron D2HW-A201D seems suitable (https://www.ebay.co.uk/itm/D2HW-A201...UAAOSw-JJafGgX). The switch arm from the old microswitch could probably be transferred to it.

 

Looks close doesn't it? I will get the old switch out & check for numbers on it at some point.

 

I doubt that microswitches are defective and if yes then with minimal occurence. There is higher chance that PCB connections have cold spots. Simply remove dual brake switch, remove PCB and then resolder all pins. I also scratched protective layer near pins and applied some extra solder to the copper tracks. Since that time cruise control works again and no more Engine failsafe mode.

Another issue in my case was that plastic "pipes" in vaacuum circuit were cracked - not the hoses itself but plastic connecting features.

Note: original microswitch works both ways, depends which pins are used. If brake pedal is not depressed then one switch is open and the other one closed. When you depress brake pedal then originally opened switch will close and vice versa. When you look at 4-pin connector then outer pins are for one switch and two inner pins are for the other switch. If you measure continuity then one is closed and the other one open. When you depres brake pedal it should change the state.

 

Hello, I have the same car and year and same issue. Did you ever find out what was the problem?
Thanks Garry

 

Hi, it's a bad idea to revive very old threads, as anyone, who would like to help you would have to read thru all the old posts to guess, what your problem is...
Better start a new thread.
So I am not going to read all the old posts and I have to guess that your "same issue" is the subject line "failsafe engine mode", aka restricted performance.

To solve this issue, you get yourself a decent OBDII reader and "ask" your X308, what the issue is.
There could be many root causes for restricted performance. The one, which I had, when I bought my X308, was - as my OBDII reader "told me" correctly - damaged knock sensors.