Hi, friends. My XK is my first (and only) car to have such advanced electronics, and I was born during WW2 so I need help with dealing with such sophisticated gear. I love it dearly, it has done 99,000+ miles and has hardly needed anything repairing. I shall drive it until I pop my clogs, or they take my driving license away, whichever comes first.

My neighbour pointed out to me that I had a brake light failure, so I replaced the bulb and it worked again. No problem there; I can deal with this.

But I had expected from reading the manual that the car should have warned me of this failure. Sure enough, it did, but not until AFTER I had fixed the problem with a new bulb. And now it won't STOP telling me. Every time I start the car, it tells me after about 30 seconds that I have a brake light failure. Using the touch screen, I remove the main warning, although there is still a small warning triangle sign at top left of the little screen between the two dial instruments. Have I got to do this for the rest of my life? Surely not!

I have put my Autel AutoLink519 on the job and it tells me there are no codes listed. Mind you, it nearly always says that. The poor thing! I get cross with it when it says there is nothing wrong, and I get cross with it when it tells me there is something wrong. There is no pleasing some people.

I am at a loss here; I may be a Chartered Mechanical Engineer, but I dont know how it detects a failed bulb in the first place, so it is difficult to work out how to stop it detecting a failed bulb when there isn't one.

I resisted the temptation to fit an LED bulb, because I thought that might upset its ability to detect failed bulbs, elsewhere if not for the brakes. Would it? I'd be interested to know, please.

So please, friends, what am I doing wrong here, or not doing right, perhaps?

If you help, I thank you.

JT

 

I've had this happen a few times on older XK's and each time the problem ended up being within the actual bulb socket itself. There is a small somewhat flexible metal contact strip that runs inside the socket that touches with the bulb electrode and evidently gets bent with time and use thereby allowing only intermittent contact. Simply get a pry tool and give it a slight bend towards the inside to allow it to make better contact with the bulb and that should square you away. Obviously check the bulb first though!

 

Thanks for this. It sounds like a potential cause of my problem, so I will give it a go and report back.

 

No, sorry kenbowen, that didn't work for me.

Does the Search system on here sometimes fail, or partially fail, without telling us, the users?

When my bulb problem started, I searched and could find nothing relevant, so I started a new thread. One result of that seems to be that I can now find lots of threads about this problem, so I've been reading of other people's problems.

I deduce that maybe the brake light bulb failure detector is very sensitive to the characteristics of the bulb; its resistance, impedance, inductance, reluctance, paint colour or something (I'm a Rude Mechanical as Shakespeare defines us, not an electrician). So if you replace Jaguar's bulbs with someone else's, you may be lucky and it will all work, or you may be unlucky in one of two ways; either it will not detect when the bulb does fail, or it will detect a working bulb as having failed. This would explain what has happened to me.

So now I shall lash out £8.20 for a Jaguar bulb, part number C2S15073, and keep the £2.00 bulb I have already bought to fit as a temporary spare for the other side should that one fail during my tenure.

I'll let you know the result in due course.

JT

 

I've never had any problem replacing the bulbs with the ones I've bought in Halfords but what you say is correct and it might be that the bulb you have chosen is just outside the spec expected by the car. Possibly buy another cheap bulb of a different brand?

Richard