2000 XJ8 3.2 122000 miles
Fuse number 3 in Engine Management fusebox (engine bay) keeps blowing the instant it is replaced. I found it when checking why front fogs weren't working. Looking online I found an explanation from a guy who had paid one of those online mechanics for an explanation. In his case his fog lamps and a/c both started working again when he changed that fuse. My a/c appears to be working fine, so what could be blowing that fuse immediately it's replaced. Any ideas pls guys n gals ?

 

I would say you have a short to ground in your fog light circuit. You got an ohm meter?

 

Ross is right, I'd be looking at each fog unit as these are down low and can let water in that leads to a blown fuse. The fastest way to check is unplug the fog each side to isolate and try a fuse then.

 

Thanks guys. Just one thing, where is the best disconnect point. I assume there will be a plug/socket behind the light fitting, but the handbook recommends taking to Jag dealer just to change the bulbs. Holy s***. It must be some job in just getting to it.

 

Update. Managed to get to back of foglamps without too much trouble, and disconnected ns (left) foglight. replaced fuse and switched on ign. Wow, fuse didn't blow. A few seconds later smoke (electrical- like burning wires) started billowing forth from down low somewhere. Quickly switched off ign and it stopped. Then decided to reconnect lamp and try again. This time fuse still didnt blow, but smoke emanated once more. Found that smoke appeared to originate from "intelligent security sounder" part no LNC 2620 AC situated down low and quite near to foglamp.
Does anyone have experience of this problem ? I dont want to keep experimenting and have wires strip themselves of insulation and set fire to the car.
What exactly does "security sounder" do. Tried the car alarm and horns went off, so it isn't that. What will happen if I just disconnect the sounder? Will it disable anything else. I am afraid to just do it in case it disables something that I cannot then re-enable.

 

Ok. Found what "sounder" does, at least in part. Will replacing it mean reprogramming fobs etc or should it just take over from old one without problems. Is it the same unit as "security module"?

 

Update (also see "XJ8 Heater not working" thread) Turned out that dodgy "intelligent sounder" was responsible for blowing fuse #3 in EM fuse box. Disabled sounder (awaiting replacement) and replaced fuse. Foglights and heater pump now working again ok. Pump is NOT listed as being powered through this fuse, but trust me - IT IS.

 

do you have any updates or information as I have the exact same problem the fuse blown was down to water in the lamp also I am told there is a security unit under the fuse box in the trunk and I know i dropped a socket under there the day before this was an issue could there be a short happening

 

Hi Paul, I have no idea if the socket could be shorting out, but would suggest removing it as a precaution anyway.
My fuse problem was caused by a faulty "Intelligent Security Sounder" This is situated just in front of the left front wing liner, down very low. Apparently it can allow a water ingress from wet roads etc., and burn out. This is the sounder that makes the beep when key fobs are re programmed. Part no. listed in thread no. 5 above. I disconnected mine, and have had no trouble since. The same fuse powers water pump for heater, fog lamps, and 2 other items that I can't recall just now, but which are listed in your "Owners Handbook" in the fuse section. It doesn't list the heater pump as being powered from this fuse, but it is!! To test the socket theory, try disconnecting the fog lamp again, see if fuse blows, if it does, make a point of getting that socket out o' there. Then next, disconnect sounder, see if it's that, as sounder and security module are probably linked in some way. Sorry I can't be of more help, but I hope you get it beaten.

 

Hi richy,

Having recently deciding to replace my heater tower( a massive job involving the throttle body assembly and inlet manifold ) I decided to take a look at the whole heating system and stripped the aux heater pump and found that it had jammed because the braided copper to the brushes was so worn down that it had cut itself as its designed to do to stop the springs catching and jamming in the commutator this coupled with the fact that I was running a battery charger while running the engine and testing through the obd port in my opinion is linked. Anyway the heater water pump had stopped working. Is this the case with yours? i.e. no heat it might be a symptom of it being about to fail new brushes will fix it JCNA Forums - Jaguar Clubs of North America brushes size looks like 4 or 5mm square by about 10mm long ish so I think these aer linked

 

same fuse as you say number 3

 

Disconnected the sounder and fuse 3 is ok and all works again.

Thanks for a great post and info

 

So pleased it worked for you.

 

Hi, I've looked for this connector but I'm having difficulty finding it. Is it visible near the front left fog light or is it tucked away?

Regards,
Wessex

 

Hi Wessex. If by "connector" you are referring to the "Security Sounder" it is situated low down just behind the left spotlight fitting, held on by two quite easy to get to bolts You will need to get under the left wing to see it, as it is somewhat hidden from above. A local garage with a lift and a helpful owner may make it easier.
Tell me, how far are you from Poole? I shall be passing that way soon and am happy to come over to yours to show you if it's not too far.

 

Hi Richy yea I am some distance from Poole. I just nipped home between lessons and removed the lower cover and found a box with a connector with quite a number of wires coming out of it. It's a large squarish connector but I cannot pull it off. Must get back to work so I am a bit disappointed at being so close yet so far. Is this the sounder? Passenger side?
Thanks for your quick reply. Peter

 

Hi Richy. All's well! I found the sounder eventually. I initially thought the oblong grey box was the sounder. Anyway disconnected the sounder and everything works perfectly.

Great thread and thanks for your offer of help.

Regards,
Wessex

 

You're very welcome Wessex, so pleased you found the problem, and that I could be of some help.