"Failsafe Engine Mode" - 2000 XKR

Sorry to crosspost this, but wondering if there might be some folks here with a '98-'03 XJR who might be familiar with this.

My 2000 XKR has recently started to show the “Failsafe Engine Mode” annunciation after driving for a few miles. This seems to occur after the engine has warmed up a bit (maybe 1/4-1/3 on the coolant temperature gauge).

Whenever this happens the cruise control stops working. I hadn’t noticed a performance difference until today, but today it was around 55F (so figure 12-15C) on the drive to work. It’s been below freezing all other times I’ve driven it like this. No check engine light, but whenever this Failsafe Engine Mode annunciation comes on it also says “Check Rear Lights” (I have, they all work, including when this turns on).

I’m not sure what “Failsafe Engine Mode” really means, but I am wondering in this case if it means that the electric water pump for the intercooler is not working, or perhaps that it’s turned off. Any insight?

Thread in the XK8 forum below:

Read the DTC(s) from the engine module.

We can all guess but the ECM has the clue.


Will there be DTCs without a CEL?

And am I going to have to buy a scan tool to read those or is there some secret code that can get that?

An Elm327 off eBay.

If you have an iPhone you need the Wi-Fi model

Sorry to chime in so late. I had this problem on two year 2000 X308 XJRs, and in both cases it was the Brake Pedal Position (BPP) Switch. The BPP switch contains two microswitches, one for the brake lights and the other for the cruise control. In a thread on another forum I saw someone say their nylon quadrant had worn, and they’d glued a piece of credit card onto it to compensate. In one of my cases that was exactly it. I only had to depress the brake pedal a tiny amount, and I could hear the microswitches click. I glued a piece of credit card onto the nylon quadrant and that sorted the problem.

In the other case the C/C microswitch was dicky. I was able to get contact cleaner into the C/C microswitch and get it working again. As a precaution I glued a piece of credit card onto the nylon quadrant and was glad I did when I realised just how little the pedal needed to be move to de-activate the C/C.

If the microswitch is totally U/S, it ought to be possible to replace just the microswitch with careful soldering, at a fraction of the price of a new BPP switch.

As an aside, although the BPP Switch is held on by just one bolt and a self-locking nut, it’s a bear of a job because you’re upside-down with your head in the foot well. Because the bolt is long, it’s a real pain running the nut off. I had no ratchet small enough to get in there. I was dead lucky finding a rubber bush which was a lovely tight fit on my ¼" drive socket, giving my fingers much more purchase, and the resulting tool made it a breeze to spin the nut off the bolt (and later back on again). I have photos of the disassembled switch if they’d be of use to anyone.