Hi all,

As above, the XJ SuperSport won't start (doesn't even attempt to turn over the engine) but there is no low battery warning message at all either. All the display loads up fine, speedo shows up etc.

There is a red battery logo there down the bottom of the display but I 'think' I'm right in saying that is always there but goes away once the car is started? Never paid attention to it before so not sure.

The car is usually plugged into a trickle charger every time when parked, apart from this time, but it has only been sat for maybe 3 or 4 days (no doors open/lights left on).

Plugged it back into the charger now and I'll wait a bit before trying to start it again.

Any ideas anyone please?

 

Just been out again and it started fine without any problems.

Very odd. Yes it has been plugged in now for about 30 mins, but I don't think that the battery was the issue the first time round anyway as there was no low battery warning.

Anyone had this happen before?

 

Could it be your key battery?

 

The only variable was that this time you didn't leave the battery attached to a trickle charger. Perhaps the battery is no longer able to hold a charge on its own, and needs replacement.

 

Don't think it is the key battery as it unlocked the car fine and allowed the ignition to come on

I think you might be right johndahlheimer, I will look at getting the battery tested

Thanks

 

You are probably right. However, I will add that when my XKR's key battery is low, it will unlock the doors fine (with the buttons on the key fob), but will have some difficulty getting the car started. I'm guessing key requires/uses more power for proximity sensing than it does for a simple button press. Fwiw, it's rare I have a low battery warning on the dash.

Strange thing is my Jaguar key seems to burn through several batteries a year, whereas my wife's 3 year old Hyundai with proximity key has never needed a new battery.

 

Hmm that's strange

Maybe you're right then haha

If it happens again, I'll try a new battery in the key and see what happens

 

Hi all,

This issue is back now, and I was looking to see if anyone has any more ideas please?

It has only been noticed whenever the car was parked for a while and not on the trickle charger... But today it happened even after it had been parked on charge for days

Once trying the spare key fixed it, today it didn't so I think it was just luck last time

Not sure if it is battery related or not because all the screens and lights etc still come on

Any ideas please?

Edit: just to add some info, whenever this happens (has only happened maybe 4 or 5 times) a combination of putting it back on the charger and waiting a while seems to allow it to start... But not sure what the actual cause is, because like I say it has plenty of power to power the xenons and all the sound system etc, just doesn't attempt to turnover the engine

Thanks

 

To test I would try this...

Next time it happens. Get in the car with the dashboard lights on etc. Then get someone to take away your smart key. Then try to start the car. It should say something like "smart key not found".

If that happens then bring the key back and try again.

This should help you understand if the smartkey is been found or not?

Also I seem to remember the manual saying that the smart key sensor is to the side of the steering wheel (where the boot release button is)... and to try holding the smart key there when you have issues?



Assuming the smart key is ok, other things to think about.....

When you get the issue, are you getting the "depress brake pedal to start" message?

Are your brake lights working ok (i.e. is it sensing brake pedal depress)

Could your start button be faulty (i.e. keep pressing it as if you were playing old skool "decathelon")

Finally (and it based on mere gussing and no fact) if you are trickle charging, are you suffering from occasional flat battery? and could this be causing key sync issues?

 

Thanks I'll check those things

It is my dad's car and he was trying to start it, when I got in to try I was going to try holding the key near the sensor, but first time I tried to start it normally it worked fine

Dad also said the brake pedal is stiff whenever the issue happens (even the first initial press), so you can tell before you even try to start it whether it will work or not. When I started it the pedal then depressed further and became soft again... Does that give you any ideas maybe?

Dad said he noticed the brake pedal message today so that might be something to look into and check next time

Thanks!

 

Just a guess, but since you have to step on the brake to start the car, if the break pedal isn't working normally, perhaps that's the issue.

 

Are you inadvertently pumping the brake pedal before pressing the start button? If so, your brake pedal wil be high and feel hard, and you might need to use both feet to depress the brake pedal far enough to make contact with the starter interlock switch. This happened to me in my XKR while I was chatting with my service adviser and couldn't start my car. He told me to press the start button FIRST and then step on the brake pedal. Started right up.

Since then, I have always pressed the start button before stepping on the brake pedal on both my XKR and XJ. Barely have to tap the brake pedal for them to start.

Try it.

Stuart

P.S. This has worked for others on the XK forum: https://www.jaguarforums.com/forum/x...se-time-57460/

 

Thanks Stuart

I think it may be what you say, about the pedal being stiff so needing a much stiffer press to activate the switch... Tested it earlier after intentionally pumping the pedal

Odd though it seems the switch on the pedal used for starting the car seems to be different to the one that activates the brake lights

Any ideas on maybe why the pedal is occasionally stiff as soon as you get in the car?

 

You may have a bad booster, booster hose, check valve, faulty caliper, or someone is stepping on the brake pedal after shutting off the engine, depleting the vacuum in the booster.

 

The brake pedal is multifunctional and has several switches. On my 2013, the brake pedal functions to (1) enable the car to start; (2) enable the car to stop and illuminate the stop lights; and, (3) operate the stop-start system.

Light pressure applied to the brake pedal won't activate the stop-start system. Firm pressure is required for the engine to shut off. By modulating the amount of pressure, you can decide whether to activate that system. When activated, you can restart the engine simply by reducing the pressure on the brake pedal (unless the computer intercedes to restart).

 

John, something you may want to try is disengaging the e-brake before starting the car. I have noticed with my car that as I engage the brake pedal, I get a little bit of feedback as the e-brake engages, making the pedal harder to the feel.

The other thing that I would check is putting a multimeter across the battery when you attempt to start the car. Ideally, the battery should be at 12.6 VDC with everything off (only the trunk open, all other doors shut). Then, as you go to start the car, you should see the multimeter drop to around 11.0 VDC as the motor rolls. if it remains at 12.5-12.6 VDC, then this is telling me that the signal to the starter is not making it there and you have an electronics issue. If the battery drops to below 12.5 VDC as you are pushing the button, then odds are you have a relay issue and the power going to the starter is being limited by either a bad relay contact or some internal resistant in the power wire to the starter. if the battery drops below 11.0 VDC, then you most likely have a bad cell in the battery and it is time to replace the battery.

 

THIS saved me this weekend and needs to be re-shared!
1st...Start Button
2nd...Press Brake Pedal

 

This seems very important - I will try this as I am dealing with this very issue right now... on my new (for me) 1 day old car - Ugh !!!

Thanks...!

 

Update...

Nope - that idea of pressing the start button before the brake pedal and then reverting to touching the brake pedal did not work. I also tried takong off the park "P" brake before hitting start with or without brake pedal touch, and that did not work either.

I did also take the key fob well away from the car and the dash then said no key fob, and so then brought it back and it did not start. I also tried putting the key fob on the left hand sde of the car (clsoer to UK passenger glove box) to see if that helped. Nada.

One PS - that may not at all important, but it is very hot here today and the car was left outside over night - about 95 F. It was however left at the dock for 4 weeks before I picked it up and it was very hot everyday then...

 

Are your brake lights working?
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