Hey there folks! I've owned a 2012 XJL Supercharged for about three months now and I'm having increasingly occurring electrical issues. When the problem shows up, It starts with the stereo speakers clicking one at a time about twice a second, and the audio (any and all audio sources) cuts out as the speakers click. It may do this for a few seconds or two minutes straight. As the stereo clicks or cuts out, the power (actual engine thrust) pulses in time with the stereo dropouts. Not total loss of power, but just enough thrust reduction to feel it. The transmission may shift a bit slow during these periods. All other auxiliary functions seem to work fine.

For clarity, I've had my battery tested twice. It is only about 6 months old and is in good condition. It was low on charge several weeks ago, so I bought a battery tender and have topped it off overnight multiple times over the last few weeks. I have been locking the car every time I am away from it and every night at home as well. These electrical issues have happened immediately after pulling the charger off of my fully charged battery.

The worst thing that has happened (about twice a week now) is a full electrical power dropout on the whole car. The headlights, engine, dash, the whole car goes dead for a split second, two, three, or four times in a row, and every time the power comes back on, the engine torque hits the transmission and jolts the car. It's not fun, and it happened at night a few days ago and that's how I know I lose my headlights when this happens. Yikes! Then I'm left with a blinking adaptive headlight warning light on the dash.

The next time I get in the car and turn it on, the warning lights are no longer on or blinking and all appears to be back to normal. If the car is driving fine, I can encourage this bad behavior by punching the gas, and running hard up to 70 or 80 MPH. When I take my foot off the gas, I guarantee I'll start hearing speaker clicks and all those other issues will show up again.

If anyone has any thoughts, recommendations, fixes, or ideas, I'm all ears. I'm a handy guy. I do my own brakes, can change an alternator, take a dashboard apart to swap a vent door actuator motor, etc. If I need to go to a shop, the closest Jag shop is two hours away, so I'd have to take a day off work and sit is a waiting room for the entire day while I wait. I'd like to give it the old college effort before I go that route. Thanks in advance for any help!

 

I'd be looking in the trunk for something loose. Or a corroded battery cable. Twist the battery connectors and see if they'll move. If it does tighten it and see if that helps. If they don't move pull them and clean them, tighten them back down and see what happens. I've always coated mine under the hood with vaseline. It eventually melts until you don't see it anymore but it seals the joint so nothing gets to them and it will never corrode. After that I might try a new battery in the smart key or just try the other smart key to see if it's losing the signal somehow. Then again the battery's in both will be the same age probably. So maybe a new battery would be best. After that I would guess maybe a ground has corroded and you'll have to dig through the manuals to find one in common with the affected systems. On the other hand the symptoms you are having might be due to a bad alternator. They fail in strange ways sometimes too. You could check the wiring on the alternator as well. Don't know if this will help but it's a starting point.

 

Thanks rhomanski! This is a lot of good stuff to think about. As I was thinking about when the problems occur, the common theme is acceleration or going down a steep hill with engine braking. These both cause engine roll. That would be very consistent with a bad ground wire connection to the engine, or a cracked ground wire. At start up or idle, the engine is stable and I don't have any issues, but under acceleration, especially heavy acceleration, the engine will be rocking and rolling under the hood and a bad ground wire wouldn't stand a chance. Now throw in a winding country road with several big hills (that's where I live) and I'm adding body roll to the equation as well. I think I'm hunting bad grounds this weekend!

I'm guessing I can download the manual for my XJ on the forum here? If anyone knows right where I should start looking for ground wires under the hood, that would be an amazing help. Thanks!

 

I did a quick check around the "world", but could not find a manual. So I got one from this thread.

https://www.jaguarforums.com/forum/x...manual-188563/

It's the cheapest manual for any car you'll find. Also because it's English and on a computer, easily the most frustrating you'll find. At least for old men like me. I either have to blow up the wiring prints so big it's hard to follow scrolling back and forth or print it and get out the magnifying glass.

It could be a ground or it could be something else. I haven't studied this car enough yet to offer a good reasoned suggestion. Case in point. My old Dodge. I could be driving down the interstate and suddenly the tach would go to zero and the engine would go to idle. Then it would pick right up and be fine for a day or two. Turned out to be a broken wire under the insulation for the distributor pickup. The computer was losing the tach signal from the distributor.

That problem was fairly easy to figure out. This car is a lot more complicated and I'm sure the problems it has will reflect that. As usual when it's fixed there will be a hundred people on here that would like to know the solution. Please don't let us down.

I just remembered someone put on a thread that they were having problems after someone worked on their's. The consensus was a bad engine ground. Maybe I can find it again. Ah yes you were in that one at the end. The OP hasn't updated it in a bit. Did you put a voltmeter on it to see what it's doing?

As far as the engine ground goes, if you only have one and it goes bad, wouldn't the power to everything simply drop to battery voltage. In other words wouldn't the lights still work but just dim a little? The only time I've lost the headlights was when my alternator quit coming out of Birmingham AL at three o'clock in the morning on Sunday night. I kept driving until the battery dropped to 8 volts and waited for the dealership to open up. $12 and a set of brushes later and I was back on the road. The headlights quit about a half mile from a phone. When I put it in park under the light the engine died. A cop gave me a ride to the dealership, a salesman gave me a ride back and the battery charged up enough to start the car. I had somebody watching over me that day for sure.

 

I'd also look at the condition of your motor mounts. The engine should be able to move a little but not enough to stretch and or break the ground connections. If you still have the OEM intakes from the air cleaners to the throttle body. Check the "bellowed" sections on both sides the spacing of the bellows corrugated section should be even on the top and bottom. Mine had gone bas after a couple of years of acceleration runs. So I have had the 2 engine mounts and one transmission mount replaced.

 

Can't figure out how to post. Anyway "04 XJ8 driver side high beam doesn't light when dip on

 

You should try posting in this forum, it's for the XJ8.

https://www.jaguarforums.com/forum/xj-xj8-xjr-x308-27/

We're trying to figure out what we own. :

 

Back to the OP's intermittent electrical problems. You bought a used 2012 XJL SC about 3 months ago. From whom did you buy it? A Jaguar or other new car dealer, private party, or used car dealer? Do you have the ownership history and service records? Did you have a Jaguar dealer perform a Pre-Purchase Inspection at your expense before you bought it? Did you have a body shop qualified to do Jaguar aluminum repairs inspect it for body, paint, and flood damage? Was the price too good to turn down? You can never rely on CarFax or similar companies.

Intermittent electrical issues can occur weeks or months after collision or water damage repairs are completed. If the seller misrepresented the condition of the car, see a lawyer. You might have a case against the seller.

Hundreds of cars were totalled by the recent hurricanes. Some high-end models have been "repaired" and sold by unscrupulous dealers. I hope yours is not one of them.

 

Your concerns are valid. That is a possibility. That's why I picked one where the Carfax showed it was imported to California and never left until I brought it out here. Hopefully the OP bought one that spent it's first life in Oregon. Where he's at is pretty moist at this time of year and I would expect he would smell a flood car by now. Unless the entire interior was replaced. Water has a way of getting into everything. Engine, transmission even wheel bearings. I would more suspect the original owner took it to the track or enjoyed spirited driving more than most. If he's on the coast of Oregon a lot, the salt air will be hard on the electrical systems. We used to coat connectors on the outside of the cabin with a compound called Amlguard. It is a water displacing compound that hardens on the back of the connectors and seals the salt air out.

When buying mine I considered a lot of different things, floods, fires, crashes. Sometimes they will cut cars in half, weld a good front end to a good back end and sell them. I remember one Father found a cheap car for his daughter, she perished in it when it broke in half while she was driving. As always the point is "Buyer Beware".

Let's hope he comes back with a simple fix and not scare him too much.

 

Hey guys, thanks again for all the feedback!

I bought the car from an independent used car dealer in Walnut Creek CA. The car was originally titled in Arizona and then lived the rest of it's life in CA. Hopefully that means it wasn't likely in a hurricane related flood zone. I contacted the Jag dealership across the street from this dealership and they were favorably aware of this dealership, and had worked with them in the past. That doesn't mean much, but at least I knew they weren't a fly by night shop. I'm not an expert, but there is not a spec of rust, corrosion, or discoloration on any bolt head, screw, lug, pipe, connector, clamp, pulley, or gadget under the hood. Even when dealers pressure wash engine compartments, tells of moisture exposure and age are typically left behind. This Jag's engine is spotless. Cross my fingers right...

I did not have a PPE done on this car. 50 lashes I know I know... I had done a couple other PPE's on cars I ended up not buying and I was tired of spending the money. And you all can understand that this car called to me! It said, "Leave your wife and let's drive to Dubai together!" (You'll be happy to know I have not attempted either of those as I would fail miserably at both) But I didn't pick this XJL... It picked me! I also paid fair market, just under Kelly Blue Book for the car. So no too-good-to-be-true price tag.

XJsss, I checked the bellowed sections of the air intakes and they do appear to be dropping a bit as they connect to the engine. Not much, maybe a quarter inch at most, but if I squat down and look closely, they do curve downwards a tad. I'm not convinced it's enough to diagnose bad engine mounts right off, but it's enough to keep it in the mix as something I need to look further at. How much of a drop did you have when your mounts were bad?

Thanks for the manual link rhomanski. I bought a download and submitted my email so hopefully tomorrow I will get the real link and start digging.

I've yanked and pulled on the battery cables in the trunk, and everything is tight and secure and clean as a whistle. I'm going to chase some wires this week after work if I can interpret the manual and post what I find. If I end up with nothing, I'll probably wave the white flag and make the trip up to Portland to the Jag dealer and let them do their thing.

I have a 20 minute drive to work every day on gently winding country roads over hills and through valleys. The only thing I have to slow down for is one School Zone. It's a Jag driver's dream. I'm ready for my car to drive like a dream too. To be continued...

 

As an update, Problem Solved!!!

I waved the white flag and took it to one of the two independent shops in town that say they can work on Jags. They took a look and told me it was a computer issue and I needed to take it to the dealership two hours north to have the computer re-flashed. Said it was communicating the wrong voltage from the battery and sending all sorts of error codes through the whole car. $50 bucks for "we can't help you", but that's more than fair for a shop's time.

I called the dealership and they scheduled me an appointment 2-1/2 weeks out. NOOO! That's too long to sit on my car with no answers.

So I called the other shop in town and they didn't think the computer was to blame with all the symptoms I described. I had 2-1/2 weeks to kill before the dealership could see me, so why not give them a crack at it. They diagnosed the alternator was putting out too much voltage (over 15 volts), and the battery was leaking because it was being over cooked. They overnight'd and installed a new alternator and new battery, sync'd up the computer to the new parts, cleared all the codes, and BAM, the Jag is as good as new! The excess voltage from the bad alternator was messing up a ton of the car's systems and as soon as the correct voltage was supplied, everything got happy. No stereo cut outs, no power pulsing, no slow transmission shifts, no pulsing lights.

This was exactly one week ago and I've put about 500 miles on the car with the Thanksgiving holiday weekend travels and not one glimpse of any residual issues. Just 470 HP and 1200 Watts of pure driving FUN!

 

So glad to hear it. That's what's so frustrating about the internet, I can't hook up a scanner to your car. Remember that shop when it comes time for a brake job or oil change or something. They actually went out of their way to think and accidentally helped you. The other one didn't as you know. I bought a scanner for my GM Tuned Port Injection engines many years ago. I'm going to have to buy one for this one too. It's interesting to read about the engine testing the EGR at certain times but cool to watch it do it.