F-Type water intrusion in trunk 2014 low mileage convertible. I opened the trunk and there was two inches of rust water in there obviously we don't drive the car much I think this was left over from the hurricane. I replaced all the modules in the trunk because I had every warning let you could have including the rear diff module the parking brake module the two fuse panels I replace them all with approved tested use goods off of eBay. When I started the car all the symptoms were gone the car now would go into gear all the warning lights were gone it was like a miracle everything was working perfectly. I decided to take it to the dealer to have it set up on the computer just to have everything checked and on the way over I got to check engine low voltage light charging problem in red. The dealers have the car for a week now and they can't figure it out. This is driving me crazy because everything is functioning properly they're telling me there is no drain on the battery so it's just a warning weight that we don't know where it's coming from. I have a notion to just take the bulb out and call the day because this is getting into hundreds of dollars or more of diagnostics yet the car is not showing any problems other than the reoccurring light after you drive it for about 15 minutes. I'm getting ready to get rid of the car and I didn't want to give up a bad car I wanted to make sure it was right for somebody so that's why I took it to the dealer but now I have this extra problem and quite frankly I'm not that worried about taking the light out because it's only a charging issue that's really not there and someday the next owner might just lose a battery I'm not that sad about that as opposed to spending thousands in diagnostics. Am I a bad person? Anybody know how to turn this damn light out? I'm trying to let them do it correctly but I'm not sure the Jaguar knows what to do they've consulted Jaguar but they don't have any answers and it seems like the most basic tests they haven't run which puzzles me. To me you put a meter on the fuse panel and start pulling fuses and if you see a drop in voltage that might be the problem but they haven't done that. The other thing is Trace back to where that warning light is coming from in the old days it would be a sending unit on the block but I guess it's not that way anymore it's probably electronic but I might can we find that part and test it it's like I'm talking to a wall. Anybody have any thoughts?

 

Are you a bad person? Based on the message being one monolithic paragraph that makes my brain hurt when I read it, I'd say yes.

For the rest, It's a bit of a guess but it might be the battery management system. There's no sending unit for the "low voltage" message, or much of anything anymore. For a baseline, I'd suggest disconnecting the battery to reset the BMS, then fully charging it on something like a C-Tek. That might be enough at this point. It not, the battery module itself might be damaged. Fresh water intrusion is bad but might be OK after the kind of work you're doing. If it had been flooded with salt water I'd be planning an exit strategy for sure.

 

Post the remaining active error codes from your OBD2 reader.

Put in a brand new fully charged battery, and the clear the codes. See what happens.

 

They have tested the battery told me the battery is good it's only a year old they did all the Jaguar updates and now they were waiting for the wiring diagram from Jaguar because they want to check the wiring harness.. this could get ugly..

 

If the car is still at the dealer then you will need to let that process finish ($).

If the battery was in the rusty water I would replace it regardless of what the dealer states, reset the BMS via OBD2, record then clear the codes, and start it up.

The damage should be localized to the trunk area with the water, and it sounds like you replaced many things and got it running, which is amazing, really...

Did you replace the BMS which is attached to the negative terminal of the battery? That would be my next step if the above failed. I would also check the ground strap from the negative terminal f the battery to the body as there may be some looseness or corrosion there. You will need to remove the rear carpet panels to get to it.

It was a closed humid environment for a while so there's that too...

 

Really need some numbers and/or codes before we can help.
Again you replaced a bunch of stuff but did not check the codes? Before or after?

It does not tell us anything when the dealer says they checked the battery. Here is what we need. First a resting battery voltage after the car has sat all night. Yes the battery is fairly new but it sounds like the car gets little use. Do you keep a battery maintainer on the car when not in use?

Removing the dash bulb might work on a 1982 chevy but those days are LONG gone! The car needs to be fixed.

It's a puzzle how a Jaguar dealer needs to wait for wiring diagrams in 2025? It's all available in electronic form as is ALL service data these days. Is this an authorized Jaguar dealer or an independent?

You might need to find another repair place.
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Generally speaking I keep it on a maintainer but not always to be honest but most of the time yes. You're correct we don't use the car it's my wife's car and I'm not allowed to touch it LOL sorta lol. I did what I could hoping I could fix it I was so happy when I replaced everything and I had no codes and the car ran perfect and nothing appeared to be wrong I took it to the dealer just to be sure and to have the codes checked and have the car set up on the Jaguar computer and on the way over that's when that light appeared. Every time you drive the car now the battery appears to be fully charged and if you drive it for about 15 minutes the light comes on but no other symptoms. I agree I may have to take it somewhere else and yes they wanted to get the diagrams from Jaguar which I didn't understand. This is just driving me crazy I just don't know what to do next. I can ask them for a voltage reading on the battery after sitting. Perhaps even though the battery tests good we should put a new one in it anyway?

 

Okay maybe the next step is the battery. I'd like to pick one up instead of paying the freaking Jaguar pricing LOL. I don't know whether to pull the car out of there or not it's puzzling why they had to wait for wiring diagrams and they could just find them online. I haven't been able to talk to the mechanic only going through a service writer that doesn't seem to know what the hell's going on so I really need to speak to the mechanic to try to get some answers. Sounds like a new battery should be first and maybe that BMS attached to the negative terminal that you're saying.

 

Okay so I suggested they replace the little module on the negative terminal of the battery which they did today and they're telling me that the light has not come on since. They're going to test it again tomorrow and I'm praying that this is solved the problem. I want to trade the car in but I didn't want to give up a bad car. Funny my friend said just pull the light bulb and I'm like well I don't really want to do that and then thinking about it I realize that they're all sealed units , u wouldn't be able to pull a lightbulb if you wanted to. But I hung in there probably cost me almost $1,000 in diagnostics but we think we solve the problem fingers crossed I'll know tomorrow!

 

Making progress and a few pictures would be a big help as descriptions are hard to follow.
We still need codes and real numbers? What is the battery voltage after the car has sat all night?
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@Agisch Thank you for providing the resolution - it helps confirm what I was thinking in post #5 and other forum members down the road who may encounter this situation.

I would keep it on a battery maintainer at all times when parked until you trade it in.

 

Okay so the dealer tested at the day before yesterday said they thought it was fixed they drove it the next morning and I had more codes rear diff headlights oh my God this is never going to end. The technician told me that the auxiliary battery is reading zero so he wants to replace the auxiliary battery and the little fuse box that's attached to it the problem is that fuse box is like almost 5 grand so I was lucky to find one online for 580 tested and guaranteed which was just luck. I've got to get the battery and I'm going to take it to them early next week and hopefully this will help but I'm not convinced. They did replace that little thing on the negative terminal that's done did not help in fact that's when we got the extra messages when they installed that

 

The thing on the negative battery terminal is the BMS, Battery Monitoring System.

You shouldn’t need the 2nd battery, that’s for the Start/Stop system. Mine died and I removed it with no issues.

 

I told them that fell on deat ears . Me neither is 2014 I don't remember it having start stop. They have me replacing the fuse box attached to aux battery too, it's very $$$ . This is nightmare. Wonder if I should take it to another Jag dealer.

 

Is that the quiescent relay box they are replacing? Used ones are a hundred bucks on eBay.

 

Again no codes? You have to understand just posting the car has codes is of no value?

You need to get and post the actual codes your car has? There is no other way to fix it.
This is a great example of why you need to DIY your car. Nobody has more interest in your car than you.
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I asked him today to please get a meter and test the voltage on the battery and let me know what it is after sitting I have not gotten the answer from him probably have to wait till Monday morning but I'll maybe actually have him tested then so it said over the weekend. The little fuse box attached to that small battery should be here by Tuesday and they were both rust covered meaning they both got wet and they're two components I did not change the small battery was reading zero and was not taking a charge so it was completely dead. See if I can get a picture on Monday and maybe some readings.

 

Thanks much and hopefully your getting close. Don't like the rust comment as we have seen many different problems when the trunk gets wet. I might have missed it but have you removed everything from the trunk to give it a good inspection for water?
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Yes I have replaced every component in the trunk and now I'm replacing the small battery and the little fuse box it's attached to it that if you buy it from the factory it's almost five grand I found it for 580 used tested and guaranteed and after pulling it out it is covered in rust water so it got wet no question so we'll replace those two components on Monday and see what we come up with. This is just a nightmare I'm having problems getting code numbers from them. I'll make sure they test the battery after sitting over the weekend.

 

@Agisch Where do you buy your parts? These are not the prices I am seeing for used eBay parts, which are a-plenty and inexpensive.