Over the years my cat has done her share of hissing and coughing up hairballs, (97XK8) but this one has me stumped.
First no Check Engine light and no codes stored or pending.
I can engage the switch and it lights up for cruise control. Press the SET button on the steering wheel and within 30 seconds it displays Engine Fault on the message center and a yellow light.
Pull over shut down and restart and the engine fault clears.
Only does it after pushing SET button. Took it for a short ride and it duplicates every time.

Has any one else encountered similar? Or, have recommendations for troubleshooting.

 

My 97 problem was different, but the cause may be similar. The cruise would work for about 10 min., then cut out and not work again until the car cooled off.

I took the throttle body out, removed the plate at end and bent the wipers a little more to increase the pressure on the tracks. They weren't making good contact when hot.

It may just be that your wipers just need cleaning or are slightly burnt, but I think it's worth a look.

 

Vern - greater minds here will correct me if I'm wrong but I believe some of the faults will not leave stored codes, so can you check codes while car is still running? I have Torque pro running while I drive so if a fault shows up, I can immediately run diags on the fly.

 

Vern, same thing happened to me. Our older models use a vacuum line to the throttle. The vacuum line provides pull on the throttle plate to maintain cruise speed. What happens is: all cruising straight or downhill with cruise control (cc) on. Start to go uphill, computer senses vaccumm to increase throttle to maintain speed. When it has no effect (can't cause line is disconnected) logs engine error, disables cc, posts amber message. Cycle ignition off/on = all resets, cc lights up, back to normal. This will last until cc is enabled, tries to accelerate and can't.

Why would this disconnect? Mine was cause engine mounts wore out. Allowed too much engine movement disconnected hose.

Hope this helps. I'll look for a photo after I post this mate.

Hohn

 

Check this hose.

 

Thanks for all of the input. I will get started sorting this afternoon and get back to you with the results. Just gloating it is a beautiful sunny day in Las Vegas. Sorry to see all of the calamity back east.

 

Hey Vern, I had the same problem for about 2 years. Finally decided to do something about it. I discovered the vacuum hose at the throttle body was disconnected. Still had the same problem so I removed the right side wheel well liner and discovered the vacuum lines were hooked up all wrong. I went on ebay and viewed photos of the three vacuum switches and the way the lines were connected, made the changes and voila, cruise now works.

Unfortunately winter hit hard after I fixed it. Its minus 13F here tonight so I'm not driving it much at all.

 

It's been awhile since I posted but I finally found and resolved the problem yesterday. I want to thank everyone for the help. I was pulling my hair out looking for the problem.
It turned out to be a pin hole in a small hose 2 inches long that adapts the plastic line to the throttle body. I ended up using a vacuum hand pump to test each line individually. I was surprised to find a vacuum leak that had no effect on the performance or kick out a code.

 

What were the fuel trims at idle?

 

Another sunshine post. I was full of sympathy until I got to this.

Graham

 

I'm not sure I'd actually recommend doing this, but it solved my problem on my 1998 XK8 (owned since new and relatively trouble free). The "Engine Fail Safe" message came up in the display and the cruise control dropped out. This usually happened after the car was warm and most commonly in stop and go traffic when the engine bay would get hot. After reading the excellent post by OregonJag on the Accelerator Pedal Position (APP) sensor, was convinced my car had the same problem. Having moved away from a triple car garage with a complete set of tools, removing the APP in an underground car park with limited tools wasn't an option.

Figuring that as the issue seems to be poor electrical contact with the "fingers" in the APP, I figured spraying some electrical contact cleaner might do the trick. The picture attached of the engine bay shows the APP is at the back and centre, just in front of the firewall. The vacuum tube to the APP is on the cap. You should check this tube and the fitting for leaks before going any further. If you are satisfied the vacuum tube is not leaking, this is what worked for me - but be careful. Electrical contact cleaner is involved and it is very flammable. I removed the vacuum tube at the top of the APP and sprayed electrical contact cleaner into the fitting on the top of the APP. Do NOT do this over a hot engine - the cleaner is very flammable. I replaced the vacuum tube, started the engine and revved it a bit then shut it off and let it cool. Then repeated the above procedure. It's been a few weeks now and the "Engine Fail Safe" message has not reappeared, even after idling in hot weather for 5-10 minutes waiting in line for fuel.

APP is at rear of engine bay, behind manifold