Has anybody heard of this, please?
I halted on sloping ground, put the car in park, assumed that the handbrake engaged (03MY) and pressed the boot release on the dash. I got out with the engine still running, but the boot hadn't unlatched. So I reached in through the open driver's window and tried the dash release again, still no joy...
THEN I switched the engine off and the car immediately rolled backwards - still in PARK and without touching the handbrake!
I'm baffled. Is this a case of brake AND transmission faults happening at once? Or is there something else that I'm missing?
Any thoughts, please?
Ollie

 

hmm... how many things have to be wrong for that to occur...

In park the parking pawl should stop the car doing that, regardless of brakes.

Something must be incredibly wrong, is my first thought.

If you engaged the parking brake (EPB) it would not have occurred (unless a faulty EPB).

You left the engine running so prevented the EPB auto-applying.

 

My first thought is the transmission innards were not fully in park. Are you able to duplicate the fault or was it a one-off?

Try playing around carefully on a grade (stay seated to use the foot brake if needed) and see what happens. With the lever in park, is the P illuminated at the base of the lever? IIRC, the indicator shows the transmission internals, and NOT necessarily the lever position. Isn't the trunk release and parking brake inhibited if not in park? If so, that would point towards the transmission not fully in park.

If you indeed have a disagree between the indicator (P) and the actual transmission position, check where the shift cable attaches on the side of the transmission. On 2003+ models, the two little bolts securing the cable are notorious for working loose.

 

Thanks guys :-) JagV8, you are right: the EPB doesn't automatically engage until the engine is off. kr98664, I think your suggestion of not actually being in Park sounds very plausible, I will check. :-) cheers, Ollie

 

More details about those bolts for the shift cable, including pictures, part numbers, and cheap jokes:

https://www.jaguarforums.com/forum/s...l-bolt-269294/

 

Yep, could be useful if that's the culprit, thanks. And I will definitely steal the CDO joke lol. ;-)

 

kr98664 I checked, and P is lit up on the gearshift surround. I'm wondering: if it wasn't in Park, would it have been in Neutral? In which case it must have been held on the slope by the EPB, I suppose, while I walked around to the boot & back? So that means it was the EPB that disengaged when I switched the engine off?
I have to say I'm more inclined to think that the EPB was never engaged - because the key remained in the ignition. So how could the car be in Park and holding on the slope for 10-20 seconds with the engine running; and then immediately drop out of Park when the engine was switched off?
On another forum I got this response: "Pressure in the torque converter now relieved, system backlash released and transmission falls back onto the gearbox lock." which I don't think I fully understand in mechanical terms. If I've got it right switching the engine off allows the transmission to relax, move slightly and thus fall out of Park. Does that sound plausible at all anyone?
regards, Ollie

 

It shouldn't fall out of park (if it was in park) as the pawl should prevent that. (I suppose anything can fail, though, but it's a very simple & robust thing.)

If you switch off AND remove the key (which I think you didn't), the EPB auto-applies unless you hold the paddle down.

If you switch off leaving the key in, I think the EPB does nothing (unless you pull its paddle up, requesting it to apply).

 

Hi JagV8,
Yes, that's my understanding also. I now think that my EPB doesn't apply itself automatically until the key is removed (which it wasn't). So that points to the transmission, "however improbable".
The insurance company has hinted at a write off, but I might buy it back if it's only exhaust, suspension & cosmetic damage. If it's a gearbox overhaul as well I'll have to think about it.
thanks for your input and perhaps I'll be able to shed more light when the car's recovered & inspected.
cheers, Ollie
P.S. the James Bond style final position

Held by one strand of fence wire (and beached on a small boulder).

 

OMG .... scary!!

Good luck whatever you do next.

 

Wow, you were not kidding when you said the car rolled! I thought you meant it had rolled a short distance in your driveway, perhaps until reaching a conveniently situated pile of pillows.

We may never decipher the exact sequence of events that caused the car to hold initially and then roll. My hunch is still the transmission was not fully in park for reasons unknown. Loose cable? Lever not fully at the end of travel? If it had bumped out of the detent, it would have been in reverse. We may never know for sure. You mentioned the P legend on the bezel was illuminated, but was that after the fact? Maybe the impact upon landing bumped the lever fully into park, unfortunately too late.

 

Yeah, Hi Karl,
It's certainly possible that the gearstick moved during the crash, and my test of the illumination was after.
I wonder if the car could have been in Drive? The ground was only gently sloping, and quite rough. Perhaps I had a wheel nestled in a little furrow - then it was poised with enough power at the wheels to fight the slope, but insufficient power to creep forwards on the rough ground.
Am I right in thinking that JagV8's loose bolts could/would result in the gearstick suddenly failing to operate the transmission or change gears? That would mean I moved the stick but the car stayed in drive - which would explain the roll without invoking a mystery fault in the park mechanism or EPB!

 

I didn't check the car immediately after the crash - mainly because it had run over my foot and I didn't fancy scrambling up & down a steep bank. However, a local fire service volunteer spotted it and went to investigate. He says the engine was running!
I know I switched it off, and I may have returned the key to the "on" position. What conditions could have started the engine on a 20m roll backwards?

 

The only way I know would be turning the key in the ignition.

 

Just a quick note, now that the matter seems to have reached its conclusion.
It seems the car was in Drive, no EPB, and was being held on sloping, rough ground by the engine (without enough power to creep forward). When the car was first found it was in Drive but switched off (the local rumour mill enlarged that to "running"). So it was a strange and worrying lapse on my part: putting it in Park is almost a reflex for me.
The insurance company did indeed write it off, but were persuaded not to de-register it because the damage was only superficial. I bought it back for NZD 1000 and my mechanic put a secondhand muffler on the RH exhaust. He also provided a bootlid & bumper in a very fetching silver colour! Most of the scratches are polishing out nicely and the gearbox & hand brake seem to be functioning normally.
Thanks everybody for your input. It really helped me figure out what might potentially be wrong (or not). Now I've still got the car (with its low mileage XF engine) and I've got some money left over to fix my old 1970 Triumph GT6 :-) A good result, really.
cheers, Ollie