Hello, I'm new to this forum. I apologize for this longread.
I'm experiencing a strange problem with my car. After idling for a couple of minutes in neutral with brake pedal pressed lightly, several errors showed up. Among them are, CATS system fault, DSC not available and parking brake(the latter works with ignition on before ABS warning light turns on).
I stopped the engine, turned the ignition on but it refused to crank. All the errors mentioned above were still in place. Removing battery terminals didn't help, so as changing battery to a good one(mine is still original and showed 11.6 volts with ignition turned on).
OBD scan showed multiple DTCs and all of them can be removed except for C0044 Brake Pressure Sensor 'A' (Subfault). Connection with the ABS module can be set up, but recalibration can't be completed(maybe the nonOEM diagnostic software I used is an issue).
I've been told to replace the whole ABS module or at least the pressure sensor(as far as i know it's not available separately)
I'd appreciate any help. Thanks in advance!

 

You need a new battery. Anything below 12.7 volts can and will trigger a whole host of these faults. You don't mention what year your car is, but if as you said, "mine is still original..." it is quite likely that it is the source of your problems.

 

Please add details of what year car, where you are located etc. Please follow protocols for first time entries.

 

+1

 

Indeed, mine has epileptic fits when the battery goes too low. I thought the ghost of Lucas had possessed it.

 

+1 battery

 

Thanks to everyone! Sorry, I forgot to introduce myself. My name is Igor and i'm from Tula, Russia.
As for the car, it's '08 XKR. I mentioned that I tried to change the battery for a one with 95 AH removed from fully operational Dodge Ram, 12.6 V with ignition on, but no luck. Maybe I need specific battery model, used by Jag?

 

Ok, "I stopped the engine, turned the ignition on but it refused to crank. " Can we assume you depressed the brake pedal? Also know, these Cats are very touchy when it comes to battery voltage.
1. Try reversing the sequence of starting, that is "depress the pedal then depress the start button or depress the start button, then, the brake pedal.
2. Insure the battery is in good condition. That is, having a full charge...12.6V might be a bit low.
3. When my '08 is not in use, I keep it tethered to a Ctek battery tender. It keeps me kitty's battery warm......
4. Are you running a trickle charger?

BTW, thanks for letting us know who, what and where.....

 

Is there any required voltage to initiate cranking sequence?

 

Not really. The whole car uses info buses to transfer data and they fault out when the voltage drops to low. It causes many different functions to act up. On mine the wipers would run, ABS faults, headlamps to strobe etc. Car just really flipped out. I know when mine cranks for a second or two or just feels like it's cranking slow that it needs a bump. If I leave it in the shop overnight with the hood up the battery will be dead in the morning. Best tip is to lock your doors once you get out of it as that seems to put the car to 'sleep'. Just the little HVAC temp monitoring fan will kill a battery if left run overnight.

I'd pull the battery leads and charge the battery overnight. Start fresh and see if the symptoms change.

 

You said you had the brake pedal lightly pressed when the issue occured, and the tried to restart the car. In that case, the brake system may be holding pressure, and you now need to 'stand' on the brake pedal to get the pressure switch to activate, and I mean literally stand on that pedal as you press the ignition button. You need a lot of force to get it to engage. Its happened to me and others on this forum.

 

A fully charged battery is approx. 12.6, or so, volts. However, it's the AMPs that crank the starter. The condition, of all cells have to be optimal to provide the amperage needed to crank the starter. This is why many suggest a battery "load" test, as opposed to simply checking voltage at the battery. A battery can appear good(?),but, not have sufficient power (AMPS).

 

Tnx, I'll try a fully charged and properly tested battery tomorrow.

 

The car is fixed, somehow! By that I mean that the guy who did it, was working when I was away. He didn't specify exactly what he did, just said that battery was the reason and after installing the good one, he did something to brake pedal sensor. Anyway, I need a new battery. Search by the number printed on oem Varta 6w83-10655-cc returns Varta battery with slightly different stats, 88AH/740A vs 90AH/800A oem. Other batteries are either taller or wider. Would 740A do the job?

 

Good to learn. The battery will get you every time in these beasts!

However, me being the "hands on" type, would have asked, specifically, what he did to the brake pedal sensor. Replace?

 

I tried to ask but he politely refused to provide an exact answer.
That thing pisses me off a little). No there where no replacements, that's for sure.

What do you think about the battery?

 

My guess is that he just triggered it manually, or as I said above, 'stand on it'.
Once the brake system has pressure, i.e. you pumped the brakes, it takes a lot of force to get that sensor/switch to close and allow the car to start.
Didn't believe it, until it happened to me.

 

That's crazy. I assumed it was just looking at the brake lamp switch for an input. It's a PITA to hop in and out of the car just to fire it up.

 

Eek,

Your mechanic didn't tell you what he did to get your car to start because it probably started normally after being parked for several hours.

Copied below is my old post from 2010.

Press the START button before you step on the brake. Starts quicker and easier that way.

Inadvertently pumping the brake pedal before trying to start the car will cause the brake pedal to feel higher up and rock hard. That makes it more difficult for the brake to make contact with the starter interlock switch, and you really have to stand on the brake pedal while keeping the START button depressed to get the car to start.

This happened to me shortly after I got my car in 2010. Fortunately, I was at the Jaguar dealer having warranty service done and when I picked up my car it wouldn't start. My service adviser explained that this is a common occurrence, why it happens, and recommended pressing the START button before stepping on the brake. You barely have to touch the brake pedal for the car to start if you press the START button first.

Stuart

 

Thanks for the reply, but the car was standing still for a couple of days prior to the other guy tried to fix it. And I changed battery the next day after this whole thing happened and also no luck. So I doubt that he just came there pushed the butter and it started. And BTW, the questions abut battery still stands. Would 88AH/740A be enough?