Jaguar XF "CANNOT APPLY PARK BRAKE" pain
January 6, 2022 | CarsTL:DR: If your parking brake gets stuck on then there's a good chance you can fix it by simply disconnecting your main battery (in the boot/truck - the larger one) for 30 seconds and then reconnecting it.
I own a 2013 Jaguar XF 3.0 Supercharged Petrol.
It's an awesome car but it's also getting a bit long in the tooth now.
I've had the car for about 2 years now with no issues so I was definitely overdue some kind of pain. The car gods don't let you drive around an ageing luxury British car without periodically demanding a monetary tribute from your wallet.
Indeed, just recently that time came. It was a fault with the electronic parking brake on this occasion. It was around 6pm on Christmas eve and I was illegally parked just to add some tension to the scenario.
I had stopped in the High Street and popped into a shop quickly. When I returned to the car and tried to disengage the parking brake I could feel nothing (you can usually feel the brake pedal lift slightly under foot). Indeed the car wouldn't budge, the parking brake was still fully applied.
I tried engaging the parking brake instead and was met with a red CANNOT APPLY PARK BRAKE error message on the dashboard display like so:
This was really fun.
I tried all sorts of suggestions from online forums (I even rang my local independant Jag specialist) but nothing seemed to work.
The only suggestion which I kept seeing was to unplug the car battery for ~30 seconds and plug it back in. Annoyingly I didn't have any tools at all on me and my mechanic had also warned me about how fragile the key coding on these cars is when swapping in a new battery so I was loathe to do this anyway, especially parked illegally in the middle of town.
I soon realised however that I didn't have much choice and that if I couldn't get the thing moved I would need a recovery truck home anyway. So I emptied the boot and located the batteries (yes there are 2). I guessed the larger of the 2 batteries was the one to be disconnected. A passer by noticed my plight and lent me a pair of pliers but I wasn't able to loosen the negative terminal nut with them.
I eventually conceded and phoned a local recovery firm. I fully expected to be waiting for a very long time but I was pleasantly surprised when the truck arrived around 30 minutes later. I explained the situation to him and he agreed that it was worth a shot to try the battery before we proceeded to tow the thing. He made me sign a waiver form and then proceeded to fiddle around for quite some time with a small socket set. He was trying to unbolt the main clamp that goes around the actual negative terminal on the main, larger battery but it's so tight in there that it seemed impossible. He was about to give up but I suggested that he should try unbolting the smaller more accessible nut on top of the negative clamp. This appears to be holding the main earth strap but it looks as though there are other wires connected to the negative terminal underneath this so I can see why he was trying to unbolt the main clamp (I would be doing the same). Anyway, it seemed to do the trick because the boot lamp went out and the car seemed to be dead. We waited the obligatory 30 seconds and then reconnected it.
I got into the car and started it. Straight away the dashboard was instructing me to hold both footbrake and apply the parking brake lever at the same time. I did so and this caused the message to disappear from the dash. (this must re-calibrate the system so that the computer is sync with the actual state of the parking brake). I gingerly pushed the parking brake level down and I instantly felt the familiar pedal feel under foot of the parking brake disengaging. I released the foot brake and the car began to gently roll forwards.
Hallelujah.
The recovery driver relieved me of £70 and went on his way and we drove home.
The parking brake has been fine ever since this incident but needless to say I now keep a small toolkit in the car in case this happens again!