"Failsafe Engine Mode" alert

Our 2000 XKR has started providing a “Failsafe Engine Mode” alert after about 7 or 8 miles of driving. I’m trying to figure out what this likely means. From a little bit of searching it looks like this might be related to the water pump for the intercoolers? The engine seems to make full power and has no issues.

What’s also interesting is that at the same time it also puts up a “Check Rear Lights” alert. I checked the rear lights (including brakes) this morning before I left for work and they all worked just fine. The fact that this turns on concurrently with the other warning makes me think this is erroneous.

Anyone have a similar issue?

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What DTC(s) logged in the ECM?? There will be codes related to the engine fault!!

Rear Lights could be a poor earth connection at one (or both) bulb holders.
Could be a fault in the SLCM for the brake lights?

bob

I haven’t tried to pull any codes off of this. There’s no check engine light that comes on, and what’s interesting is that the code resets every time I start the car. So for example at lunch I ran an errand. The dash was clean, no codes on either running to the store or running back to the office. I am sure it will come on on the drive home again.

It’s been a while since I’ve dealt with these, but I seem to recall a check engine light for DTCs.

When the check rear lights warning comes on have you stopped the car but left the engine running and looked at the rear lights? They might be showing the brake lights.

Check the battery condition. Old/weak batteries can trigger spurious warnings.

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Good thought, I’ll take a look at the batteries. I don’t know how old the battery is on this car. It has always started just fine since we bought the car (about 3 months ago now) but on these computerized cars things can be weird.

A couple of other notes:

  1. When the Failsafe Engine Mode and Check Rear Lights indications come on, the cruise control stops working. The indicator light by the shifter goes off and it won’t work
  2. It’s been cold (below freezing) every time I drove it with these lights on until today. Today it was in the mid 50s (F, not C… so figure about 12-15C) and today I really noticed it being down on power from a stoplight. This makes me think the electric water pump for the intercoolers isn’t working

My first question: What exactly does “FAILSAFE ENGINE MODE” mean? I’m not getting a check engine light with this. Would it still throw a DTC?

Can this be triggered by an inop intercooler electric water pump (which I know are common failures) or, if this is triggered, will it turn off that intercooler electric water pump on its own?

And yes, when the “Check Rear Lights” is on (keep in mind: these ALWAYS go on together) I’ve confirmed all the rear lights work. So that also makes me wonder if there’s a computer/module that’s going out that somehow controls both those items (the rear light diagnostics and the electric water pump).

Check the brake light switch, this has 2 contacts, sometimes the CC switch fails open which is what cuts the CC when you hit the brakes. I had that happen on my XJR and I cleaned up the micro switch and it stopped throwing the warning, I don’t recall it throwing a code for that as it is just a micro switch.

My experience with failsafe mode. This is just some insight and possible cause! Sometimes you won’t get a check engine light. But you will have a code it has come from experience believe me! It’s coming from a sensor or thus a electrical issue. Normally when this happens in my occasions is the TPS. SOMETIMES it won’t do it for miles and miles then somedays it becomes a newsonze…constantly on short drives and the cruise control quite it’s part of that system failsafe protect mode! Do not spend 1500 dollars replacing TB it’s something less expensive and if your doing it yourself you can save your self a few quid for beer after the repairs. Has for brake light this is also common on ours normally the lower side light on rear right. A bad bulb connection. You can buy used TPS at some places but finding a xkr at picknpull is few and far between. You can also test TPS with scan tool it will give you range on the cheapys. You will have one code which stays there that means the system is ok. Good luck mate

It is true that the “failsafe engine mode” warning is often triggered by a bad throttle position sensor, but when that happens it is accompanied by a massive reduction in engine power - like running on just 2 cylinders instead of 8. It can be almost dangerous if it happens on the freeway. The original poster isn’t experiencing any power loss as far as I know.

If it were the TPS, it can be rebuilt for $400. I had that done and it worked beautifully.

Dave

If a TPS failure on these results in a massive reduction in power, that is definitely not what I’m having.

I ordered an OBD2 reader which should arrive next week, and then I’ll start looking into what DTCs show up, then I’ll report back.