another intermittant failsafe
 

As with many others it seems, I am getting a frequent "failsafe" message. I bought an "approved" ODB2 scanner and have checked for trouble codes 6 or 7 times. With car running and "failsafe" maessage on. Code is P1111 which is "system test passed". My code reader also says intake air temp sensor (intermittant high voltage) is a code P1111 for Jag. Does someone have a link to locations for IAT sensor? I would like to clean the throttlebody and related sensors, is there a link to a how to?1998 XK8, 90k miles. Failsafe does turn off cruise control, but performance seems unaffected.
Thanks loads for any help.

P1111 is "System Test Passed"(Not IATS Related) on a XK8-XKR. FWIW, The IATS Sensor is paired with the MAF Sensor at the Front of the Air Tube. The Connector at that location connects both Sensors. You can clean the Connector with Electrical Contact Cleaner. You can also clean the MAF Sensor with MAF Sensor Cleaner. Do NOT touch the Sensor itself, just spray with the cleaner.

Failsafe Mode is related to the Throttle Body. There are 4 Sensors on the TB, 2 Pots for Pedal Position and 2 Pots for Throttle Position. You can clean the Connectors with Electrical Contact Cleaner also.

A sticking Throttle Plate can cause problems. Clean the Throttle Body with "Throttle Body Cleaner" only. With the Key in the "Run" position and the Engine NOT Running, Press the Accelerator Pedal to keep the Throttle Open to allow access for cleaning. Apply the Cleaner to a rag and clean the TB. do NOT spray the cleaner into the TB.

The Contacts on the TB connector(s) are prone to corrosion. Jaguar has a kit to retrofit the harness connector with gold plated contacts in extreme cases.

Check the brake switch, failure turns cruise control off.

thanks
 

I apppreciate the information. I will take a look at the TB and related sensors. Oh, and the brake switch too.

Thanks
Will

Pay close attention to the electrical connectors on the throttle body. I chased intermittent failsafe and other messages that ultimately turned out to be a faulty connector on the throttle body. It felt like it was seating correctly but the tiny internal retaining clips were broken off and it would work lose at random times. I worked up a retaining screw set up and the problems went away for good.

Will - have you solved this? My ride now has the same symptoms.

No luck, so far
 

Nope, it is still coming on intermittently. I have tried: new plugs, cleaned MAS and TB, cleaned all connectors on TB assembly. I will try the brake switch next. That is a bit of a pain as I am 60 and don't bend that well.
Will

Will,

Thanks for the smile. I'm 55 and quickly beginning to understand the bending thing. Even though I exercise (not just turning wrenches either), flexibility is difficult to maintain! Reminds me of a joke, "You know you're getting older when you bend over to tie your shoes, you think about other things you can do while you're down there."

I've been wondering about the brake switch myself as there are times where I can predict I'm about to go into failsafe mode. Those times are where I'm going down the road and the cruise control just won't stay engaged, just like I'm tapping the brake pedal. Sure enough, within a few minutes the message is on the display.

I'll try and get to the brake switch assembly in the next few days myself. Unfortunately it's behind in priority to the 1988 F350 diesel that yesterday started spewing fuel all around the engine compartment! The F350 is a crew cab with a long bed and is certainly not a daily driver, but it has its uses.

big trucks
 

I have a 2000 e350 extended wheelbase van with the V10. I love my ford truck. Yes quite useful.
Cheers
Will

My FAILSAFE ENGINE MODE Solved.
 

Brake switch assembly.

Thanks !!!!!
 

I want to send out a big thanks to all responders of this thread. I finally replaced the brake lamp switch and the intermittent "failsafe mode" is gone.
I also replaced a faulty fuel tank sender and have a working fuel gauge again!
Very easy install on the '98 XK8 convert.

THANKS!:icon_lol: