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Average annual percentage of humidity is 80%. Wow! A "wet" history was a good guess.
Not necessarily a "leak". Possibly condensation.
Theory: if a circuit board is cold when a warmer, high humidity front moves in, condensation will occur on the board. There are various scenarios where humidity could be "trapped" in the cabin, including an actual "leak" that may or may not touch the board.
Where to look: So, security related functions continue to work. The PCM is generally weather sealed. That leaves the Front Smart Junction Box (FSJB) and the Rear Smart Junction Box (RSJB) as the most likely, critical modules. The FSJB is located adjacent to your passenger's left foot and the RSJB is located behind the rear seat center back cushion.
If you are comfortable doing so, you could disconnect the battery, remove and disassemble each module and check the circuit board for signs of moisture damage/corrosion.
It would be impractical to seal the module housing to seal out moisture. However, if signs of corrosion are found, after thorough cleaning, the board itself may be sealed. Specialty "clear coats" are available for the purpose.
Note: if you were to install replacement modules, the replacements must be programmed using SDD.
Hi and Thanks for the reply. Yes I'm convinced it is a water issue as its been left outside these last few days and it's been fine (been surprisingly dry for the UK recently). Going to strip out the Front BCM over the weekend and check for corrosion. Thanks again.
Hi, Unfortunately still having problems though at one point I thought I had solved the issue but to no avail. I purchased a copy of the SDD software but to be honest It's like giving a duck a mobile phone I really don't know what I'm doing. I managed to get it connected and scan the vehicle and one of the faults it came up with was the battery backed sounder. Looking on various forums it appears this sounder can cause electrical mayhem when it fails, so as it's an easy fix I whipped it out, reconnected the battery and the car burst into life and has been fine all week.. no issues Hooray. Thought I'd pop out this afternoon as the sun was finally out in the UK, opened the front door and the blasted sidelights were on again and I have no ignition. Seats will only move in little jumps as do the windows. I've connected the SDD up again and it's telling me there are many modules not responding. Can anyone give me an idea how I can fault find this issue further, could it be a key issue and it's not being seen by the car? It's the sidelights being on which is the mystery. Incidentally I was poking around the SDD as if I'm feeling brave I might have a go at adding the AUX facility, when I looked at what was required the SDD dropped a message on the screen which exactly matches my problem. I'll try and attach the messages to this post.
Many Thanks Ian
This appears to be your problem. I guess they started by whacking on the instrument panel to no avail but appears it was a loose connection in the gauge cluster.
Ah yes Sean I spotted that post and had the instrument cluster out this afternoon. No amount of manipulating the cables or plugs could get the fault to reoccur. I inspected all the pins in the plugs and the cluster and they all look perfect. I'm going to bite the bullet and buy a second hand cluster and have a go at recoding it. What could go wrong!
Well I have a bit of an update but not sure what it means. Sometimes the car would work every time, open the doors, jump in press the starter and away we go, other-times it would be open the doors, press the starter and nothing no ignition i'd have to disconnect the battery for a while before getting the ignition back up but there was no rhyme or reason as to when it would fail, the worst time being on a very busy petrol forecourt and i had 2 pumps blocked off, I was not very popular. I have though after rewinding my actions realised that if i open the car with the smartkey standing right by the driver door the car will always work, ignition on and off we go 100% but if I open the car from a distance (across a garage forecourt for instance) or from the other end of the drive it's 100% fail everytime. It appears whatever signal sent from the smartkey to open the car works ok but wont energise the circuits for the ignition. I don't get Smartkey not found messages unless I start the car and take the key away as you would expect. In case it was the smartkey I had a local company supply one, it took the spotty teenager 5 mins to code it to my car with his laptop, cut the key blade and was gone before i'd drunk my tea, all for £250 but it was to no avail as the new key performs exactly the same as the old, but it reassuring to have a spare. I have more confidence with the car now I know to make sure i'm standing very close before opening the car but it is a little inconvenient. Any ideas?
Have you have checked all grounds and the distribution circuit in complete?
Have you had electrical work done?
The Electrical Guide for your car is listed in the stickies above.
If this is not your forte, may I propose you take it to a professional with late Jaguar electrical experience…
Different vehicle all together but FWIW I had the same issue on a 2008 f250 it would consistently start up with no issues at all then one day nothing, no door chimes or gauge lights, just an airbag light.
Day or two later it's fine. After much internet research everything pointed at the gauge cluster. There is a company in New York, I believe it's called United Radio??? I called them up and found it's a very common problem. Soldering on the resistors needs to be redone (I believe they said humidity can cause the issue to appear?). Removed the cluster shipped it to them and received it back in 3 days for a cost of $180. Worked fine for years, passed the truck to my son in 2016 and about 3 years later same thing happened again, he replaced the cluster and hasn't had an issue since.
Hmmm it does seem to keep coming back to the cluster being at fault, though setting up a replacement does somewhat frighten me, especially the bit in the procedure where you have to erase all the keys. But it looks like it's my only option.
That's why I didn't replace the cluster, I just took it out and sent it to them, they soldered it and sent it back and I just plugged it in. All iwas fine, no need to set the mileage or calibrate/code anything for a new cluster.
Hi Again, After spending a happy Sunday cleaning and polishing the car, when I went to start it I had no ignition the screen was stuck on the Jag logo and the centre panel wouldn't light up and strangely the side lights were on though the lighting controls were off. I could lock and unlock the car with the fob and the headlights would come on, again from the fob but no other controls would work.
I removed the negative lead from the battery and when refitted the side lights were off and the car was happy again, after resetting the windows and clock the car ran fine, possibly even better than before as the odd convertible top issue had vanished and it worked beautifully.
Forward to Tuesday morning when I opened the garage to take it for servicing and the battery was completely dead, recharged the battery and refitted it and same fault as before, side lights are constantly on but no ignition, car opens and locks on the key fob.
Should the key slot in the centre armrest reset the car because if I put the key in it does nothing.
Battery is fine with 12.8 V and is only a year old so don't think it's that, its the strange side light issue which I can't Understand.
Car did this last week when I went to collect it but reset after removing the battery lead...seems something has properly broken now..BECM?
Any ideas very gratefully received.
Regards
Ian
the fuse box in the back seat called the rear junction fuse box is going bad or you need to replace the fuses cause mine was doing the same thing when it leaked water through the back window of the convertible top.Your jag sound like it went into a fail safe mode just like mine did.You either need to check all those fuses in the back seat fuse box or replace the whole thing if the fuses not working.They very cheap to buy a replacement if you buy 1 used and u can put it in yourself if you know how to unscrew it and disconnect all the wires from the old 1 and attach all the wires and correct fuses back on the slots on the replacement fuse box.Your bio says you have a convertible,so i know it's probably leaking water on to the back seat judging by the cars age
Last edited by Barry Leftwich; Mar 29, 2022 at 04:47 AM.
SpitJag,
If understood correctly, failure to start is accompanied by low voltage on an apparently good battery.
So, it sounds like there may be a significant Quiescent Current Drain.
A current draw problem is sometimes an operator malfunction, such as leaving a door open for an extended period of time or leaving an OBDII reader plugged in, etc.
Current draw may also be software not shutting down or a defect in a control module.
There are Jaguar TSBs for Quiescent Current Drain in various models out there.
However, a very good U-Tube video on troubleshooting current draw problems is here:
I would also recommend a simple plug-in voltmeter for the cigar lighter.
It won't work when the system is asleep but will confirm electrical system health when energized.
