2006 XJ 2.7TDi (UK)
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Hi all, I had a MAJOR issue today. I had a TOTAL electrical power outage while driving!!

It all started this morning - freezing cold day, engine was sluggish to turn over and didn't start. As the battery got flatter, all the lights, bells and whistles started, so I got the jump leads out and boosted the car from my wife's. She started up immediately and we went out shopping!

An hour later, got back into the car and she fired up no problem and we headed home. Enroute, I noticed that the SatNav screen went black and then came back on, then off again. Soon after, the Reduced Performance light came on and then the DCS light, then the SatNav Screen came on and went off again.

Then we felt some very odd juddering and noises, followed by total blackout of all the instruments. Steering went heavy, lost assisted braking and just rolled to a dead stop. TOTAL POWER OUTAGE!

Nothing at all worked - not even the interior lights, nothing! Opened the boot manually with the key, undid the + terminal on the battery to "reboot" the car and noticed small sparks when reconnecting as iff something was drawing what power was remaining in the battery.

Walked home, got wife's car and connected the jump-leads. Tried opening doors with the remote but nothing! Opened door manually, tried key in ignition - DEAD as a Dodo.

Stood scratching my head for a couple of minutes, then went to the back of the car and noticed the Jump-Lead smoking!!! Quickly took it off the battery and the leads were HOT even though I hadn't even tried to crank the car over!!

Something seriously wrong I suspect. Had to leave car where it stood (after disconnecting battery. Called the best Auto-Electrician out but he's not answering phone (between Xmas and New Year), so I'll have to wait for him to get back to me.

Anyone ever heard of this???

 

Sounds like a short somewhere - kind of thing that can happen on any make of car, though rare. Trace wiring to find short...

 

Only think that would draw massive current would be the alternator I would think. How old is your battery - modern cars need a really good one, not one that will just about start it. Cold kills batteries. Earth points can also be a problem near the front lights. Hope you get it sorted.

 

Clearly a very big short circuit. Everything on the car is fused except the alternator and the starter motor. A diode prevents current drain via the alternator, but obviously this could have failed. Could also be something to do with the starter motor. These take a few hundred amps to start the car.

Basically, you need an auto-electrician !

 

I wouldn't exclude the possibility of the battery having failed in some major way.

 

Could be a dead battery with a short inside it.

 

Basically get yourself an electrical drawing and multimeter. Big faults like this generally are very easy to find, its the small niggly issues that are the most difficult. Just work your way from the battery and you will find it

 

I suggest you get the alternator tested. May not be a short if you are lucky.
The battery may be so far gone, as Partick the Cat suggests, the alternator could not charge it and/or the alternator is bad.

 

Hi Tom,

Sorry to hear of your malfunctioning Jag, but I echo the suggestions that the alternator may be a primary suspect. If a diode fails in the rectifier (inside the alternator), a constant current drain can be created even when the ignition is shut off. This will quickly kill the battery. On a friend's Lincoln, I diagnosed this condition when I discovered a parasitic current drain of 3 amps, which is easily sufficient to make jumper leads hot.

All the electrical and electronic systems in a modern Jaguar require a strong, healthy battery, so if your battery was fried I would expect all of your systems to go dark.

There are plenty of YouTube videos that show basic tests you can run on the alternator and battery if you have a meter that can read DC and AC volts as well as resistance (ohms), but if you have limited experience I would highly recommend seeking out a competent shop that specializes in automotive electrical systems. They'll be able to diagnose the cause in the shortest amount of time and with the least guesswork and wasted money.

Please keep us informed.

Cheers,

Don

 

Hi Tom it seems I have the same fault as you on exactly the same car, did you fix yours what was the fault. Regards Rodney.

 

Believe there are three major fuses in the rear of the trunk, not far from the battery.

That could cause things to die on you, one goes to the starter, also a constant hot.

 

Thanks Wingrider

The 3 main fuses are intact, the short is downstream from the megafuse box taking 160Amps!
Probably the big cable that goes to the starter and alternator, I will check tomorrow.
Regards Rodney

 

Small sparks when reconnecting the ground terminal to the battery is normal. My first impression (without reading the subsequent posts) was that your battery may need to be replaced. I mean, perhaps the battery has an internal short?