Hello all...
Started off for work this morning and got about 500yards, turned left at the first set of lights and promptly lost all electrics on the car. Engine was running but everything else was dead, no headlights or anything.

So... let's start panicking! What could the issue be for me to investigate when I get home later? Water ingress is high on my list so far given the rain we had last night... but where would it collect?

Looking forward to it

Cheers.

 

My hunch is your charging system is on the fritz and your battery ran way down. Not positive about Jaguar, but on other vehicles from the Ford family of this era, if the battery voltage drops too low, many non-essential functions are inhibited to preserve battery power to keep the engine running.

You can expect to lose lights, radio, HVAC, etc. in order to keep the engine running so you can pull over when safe. But as smart as the car is to be able to protect you like that, it doesn’t bother informing you. It just kills all those functions and leaves you scratching your head.

Did the engine ever stall on you? Were you able to limp the car home? Did you try to restart it and did anything happen?

I would suggest checking the battery voltage before doing anything else, to see if it had been run down. If low, but you can still start the engine, check the charging system.

If the battery is too low to start the engine, hook up a charger overnight, try again, and then check the charging system.

 

Admittedly the car does fairly short trips between starts, 10miles or so to work. During the winter the battery sometimes needs a charge off the car, but I always get a warning from "cruise unavailable" etc first. This seemed more terminal, but it was similar when the alternator failed last year. This was replaced with no issues since.

Other forum suggests battery cables in the boot.

Will check battery etc later and report back.

Thanks for your help...

 

Pull the fuse for the transit relay.

 

Sorry, to answer your questions... it didn't stall, the electrics all went dead but the engine was running and I just went round the block and limped it home less than a mile. I didn't try and restart it, I was worried I might cause some electrical damage if there was water involved. I did turn the ignition to position 2 though, and the dash lit up as it normally would prior to starting.

 

Battery says 5V!

I would presume that if it has a drain somewhere and it did so over night, it wouldn't have started this morning. It then ran that very short distance but gave none of the usual low battery warnings for cruise control/ABS/DSC etc, it just died, like a switch was flicked.

Could the battery have suffered some kind of catastrophic failure?

First step is buying a new battery I guess and see if it starts.

 

Try charging the battery for 8 hours at 2 to 5 amps and then retest it. There needs to be a minimum of 12.6 volts for everything to function normally.

If you do get a new battery, charge it as well because many batteries sit on a shelf at the parts house for months before being sold.

 

Wow, 5v is über low. That's far worse than just being run down. I'd lean towards your theory of some internal failure. Since the battery had enough oomph to start the engine just moments earlier, that seems to point in that direction.

I'd suggest having the old battery tested, just for giggles. It would be good to hear the guy behind the counter confirm it has failed.

Other than a battery failure, I can't think of too many scenarios that could deplete a healthy battery so quickly. Even if you had a heavy cable with a direct short to ground, I think the megafuse (450A) would open rather quickly, long before the battery could run that far down. The only other thing that comes to mind is one of the diodes in the alternator. If shorted across, that would run the battery down quickly, but I still don't think that would happen as fast as you've described.

When all of this happened, do you remember seeing the little red battery indicator illuminate? From the few times the indicator has been mentioned here, it seems it is not very reliable. It seems to work okay for most minor fault scenarios, but when the $#!+ hits the fan and the charging system is totally kaput, there's no warning. It's as if the system has to be healthy enough to tell you it's a little sick. But if too sick, it can't tell you.

 

Battery replaced, car starts, battery charging well at 15+ volts.

However, bad things have happened. Multiple error messages for all systems, ABS, DSC, CATS, gearbox fault, park brake etc. Climate control and nav screen inoperable. No instrument gauges, no windows, no remote locking. Head, tail and brake lights on permanently.

SDD can't communicate with ATC module.

Fault codes include B1400, C1517, P02C1, P1794, U0155.

And since I'm up for work at 03.30 that's as far as I'm getting til tomorrow, when I start looking for pools of water and blown fuses I expect.

Any useful pointers please fire away!

 

Link to video of the aftermath!
https://youtu.be/eLeeOVP0YxI​​​​​​

 

Did you try this yet?

https://www.jaguarforums.com/forum/s...rouble-214690/

 

Hmm, 15+ is pretty high. What year is your car? Early models have a simple charging system, with a fairly steady voltage around 13.5v. Later models have a "smart" system that puts out around 14.5v at first, tapering back to 13.5v after a few minutes.

One concern is a failed alternator diode. Perhaps it could have drained the battery faster than I thought. But even worse, it could let the alternator pump out some nasty AC ripple. This could be responsible for at least some of the many other faults present. A failed diode can certainly give a false indication of high charging voltage.

Checking for AC ripple is a piece of cake with the right test equipment, but not so otherwise. Some multimeters can pick it up, but not many. I've got a dozen different meters, but only my Fluke 87, an Ancel BA101 battery tester, and an actual oscilloscope can do it. The problem is AC ripple is actually a series of huge spikes, and most meters are anticipating a smooth sine wave pattern.

So how can you test for this potential problem? A few ideas:

1) Monitor battery voltage with the engine off. Some (but not all) diode failures can run the battery down quickly. With the battery connected as normal and engine off, connect a voltmeter to the battery. Put the meter outside and close the trunk lid so the various modules can go to sleep. The trunk seal has enough give so the meter leads won't get crushed. I think it takes 45 minutes or so for all modules to go to sleep. Before that, you should see a gentle decline, followed by a fairly steady reading as the load drops off. If the reading drops rapidly at first or never stabilizes, suspect a bad diode.

2) A damaged module could mimic the battery drain of a bad alternator diode. You could pull fuses to disable the modules.

3) With a fully charged battery, remove the serpentine belt and run the engine briefly. There will be no coolant flow, so limit the run time to only a minute or two. You're looking to see if all those other faults suddenly behave themselves when powered by nice smooth DC straight from the battery. If now good, that means the alternator was pumping out excess AC ripple.

4) If the car is safe to drive as-is, take it to a place that tests and sells batteries. Nearly all modern pro-grade battery testers can check for AC ripple from the charging system. Call ahead to be sure. If the guy doesn't know what you mean, try elsewhere. It's a very common test as part of a charging system checkout.

 

I've overlooked the charging voltage being way too high. It was in the 16s before it settled down to 15 something as well. I'm worried I've properly fried something now but it certainly sounds like the issue.

It's an early 2006 car, not sure what charging system it has.

I'm reluctant to start the car again to test for anything AC related. I think I may have it towed to a garage who knows what they're doing.

The irony is I was about to sell the car!

 

One good bit of news is that you did not lose all electrics - the engine would stop instantly if you did.

 

Yeah, 16 is way high. It's very likely your old battery was repeatedly cooked, and possibly boiled dry.

I wouldn't be too concerned about causing any damage by starting the engine. If there was any damage, it's already happened. But most likely, you've probably got garden variety stuff like blown fuses. It's easy to convince yourself of all kinds of horrible things happening, but that may not be the case. With some types of DC motors, when the voltage supply drops, the amperage increases because the motor still tries to do the same amount of work. Excess amperage will blow fuses, as designed. So step back from the ledge until you can do a little more investigation.

Another thought for troubleshooting, and perhaps this will put your mind at ease: Don't even bother starting the engine for now. Just concentrate on the pre-start faults you have presently, such as Gearbox Fault, etc. With any luck, you'll also find whatever is responsible for all of the other stuff.

For example, look at the fault codes you listed. The only one for which I could find any details was P1794. Look here, and scroll down to page 73:

http://www.jagrepair.com/images/Auto...tos/P20003.PDF


P1794 could be caused by something as simple as a blown fuse. Per the above, follow the power source to connector GB2-9, at the Transmission Control Module as seen in figure 02.2. That leads you to fuse F15 in the Primary Junction Box, just outboard of the US passenger's feet. So to get started, look at that fuse and see if it has blown. Wiring diagrams here:

http://www.jagrepair.com/images/Auto...cal-2006on.pdf


One of the other codes you listed was P02c1. Is that a typo? Usually the code is one letter followed by four numbers.

 

One more thought: Make sure to keep the battery fully charged during any troubleshooting. If there had been some electrical drain that ran down the previous battery, this fault is likely still active and will deplete the new battery, too. You could inadvertently induce a bunch of new problems due to low voltage, but not realize it.

 

Any updates? I'm curious if you (or your mechanic) have made any progress.

 

Hi... update as requested, it is fixed... alternator was obviously overcharging so that had to be changed before anything else could be investigated. That solved the problem on its own thankfully, no other faults remained once it was charging the battery properly.

However, the car is now for sale. Sad times but needs must....

 

Thanks so much for the update. Glad to hear you got everything sorted out. Even more good news that all the new faults cleared on their own with the new alternator.

Do you think the new problems (blank nav screen, gearbox fault, etc.) were caused by the new battery being run down by the old alternator? I'm just trying to make some sense of the whole situation, and that's the only thing I can come up with.

 

It was an old battery worn down by a 2 year old reconditioned alternator, but yes I think that caused all the problems. I'm sure you're aware how sensitive these cars are to poor electrical supply, and with a near dead battery and an overcharging alternator it was having none of it.