2014 XJL Supercharged V8

Rough morning.... I'm hoping to find some advice on here of where to start with this issue and what can be the areas to check. The issue started with a dead battery. While I had the battery removed my old school father thought he would help by placing a spare battery into the car before I could get to him I heard a little click from the trunk area. The battery he was trying to use was reverse post so he hooked the Positive to the Negative side Adding to my frustration, I inadvertently shut the trunk forgetting there's no key whole without power....lol... Long story short I got the new battery, attempted to use both the jumper under hood method and behind rear seat trunk bypass wire to get it open with no success. I had to use the method of removing the wire loom, routing a hanger through the trunk lining to pull the release....Now I have the new battery installed and no power at all..... I'm new to this site but I tried to be as specific below as possible....I do have a scan tool but its no use without being power.... Help!!!!

Symptoms: No electrical power at all.... No door unlocking, no interior light.....

Battery: New showing 12.5 volts
Steps Taken: Rear Trunk

1. Checked the continuity on all fuses in trunk fuse box using multimeter
2. Checked the continuity of the mega fuses in the battery junction box, only found one 40 amp fuse bad (Audio Amplifier according to wiring schematics). I did swap with a good one just to see and still no power....
3. Checked the continuity on both mega fuses on the Positive battery terminal.
4. Battery connectors are fine and show no burn marks
5. Checked the ground wires in trunk and they show no burns

Steps Taken: Under the hood

1. Checked the continuity on all fuses in the fuse box using multimeter
2. Checked the continuity on the 100 amp mega fuse in fuse box
3. With battery hooked, verified 12.5 amps at the Jump Start location

Steps Taken: Behind Rear Seat

1. Checked the continuity on all fuses in the fuse box using multimeter

 

I have nothing to add, but I commend you on the thoroughness of your post. There are plenty of brilliant minds on this forum who should be able to reply with some "next steps" based on what you have already done. Best of luck.

 

Thanks KalamazooJag

 

It would be worth subscribing to JLR TopiX for a day or two, to give you all the technical manuals including schematics & descriptions of the electrical system, to help you know the system & where you could check for continuity & such.

I imagine that the system is robust enough to avoid major damage if this rare-yet-inevitable action happens.
Have you tried disconnecting the battery cables & touching them together, maybe to un-latch something? Couldn't hurt.
Example of a JLR TopiX schematic...

 

I would start with a multimeter and see where you do and do not have power. It is possible that you blew the mega fuse for the front fuse boxes and that would kill power to most of the car. These are like 150 amp uses that are bolted to the fuse box. But, if you have power to most of the fuse box, then we are looking at a module that has bitten the dust and this is where a SDD computer will test all the modules and tell you which one it is having issues with. I would be venturing to guess that you are having issues with the body control module if it is a module issue.

 

Elecrical wiring diagrams are available from Sticky section from this forum.
I would do like Thermo wrote: Start measuring where you have power. All fuseboxes have positive input wires. Check these first.
I wish it is something simple.

 

Thanks, I was able to find some schematics on here and also in Identifix. I figure I am going to have a heard night but will retrace my steps with the diagrams. I will post what I find.

 

Dan,

I might be wrong here...but, it's worth a try.

A couple of years ago I walked away from my car and tried to lock it, nothing happened. I walked back to the car and it was totally dead. The only thing I could do was open and lock the drivers door using the 'emergency' key. I had the car towed to the local dealer and left it with them. It turns out that the KVM (Key Vehicle Module) had been corrupted [Dealer thought that someone was attempting to clone my key as I was locking the car].

From memory, they did a hard reset, that allowed the OBD port to come back on-line, then reprogrammed the KVM and keys. I got the car back the next morning.

If the KVM is corrupted, the car is a brick on wheels!

wombat

 

Good evening, so I took 12Jagmark's advice and it worked. I'm thinking the way the mega battery junction fuse case attached to the (+) battery post sits horizontally allowed the broken piece inside of the fuse to connect giving me false continuity. Once I tapped both unhooked battery post together, I heard the loose piece in the fuse. When I rechecked the continuity there was nothing This would explain no power and why the other regular fuses were still good. Now my problem has been locating the replacement 350A mega fuse at the dealer. Jaguar's system only shows the 400A fuse for my car and the parts guy who was puzzled took about 30 minutes researching with their technicians who stated they have only seen the 400A used. He then stated this is probably only for my specific fuse box and I would have to order the complete setup which is about $1200 to $1500..... I'm debating replacing the 350A fuse with a 400A????? My vin number pulls up the 400A in the system..... I can grab the 400A today from the dealer or wait 5 days for the same 350A mega fuse I can source from DEL CITY Electronics who has the replacement.... I'm weighing the risk.....

Picture below I have already removed the 350A fuse.


I used Identifix's diagram which matched what I have but the dealer does not show it??

 

How bad do you need your car? If it is something that you need to use it now, then I would grab the 400 amp fuse, put it in and drive the car until the other shows up. The difference between 350A and 400A is minimal and if you are getting up into that range, odds are, you are going to go well above 400 amps and it just doesn't matter and the odds of having a failure that would take you just over 350 amps is unlikely. If you can wait, then I would save the money and just wait for the 350 amp unit to show up.

 

You can find them on eBay in 350A or 400A. Most ship from China. But a few ship form US. Maybe even expedite. For example. https://www.ebay.com/itm/4Pcs-MEGA-C...-127632-2357-0

 

Boy are you lucky!!! Glad it was just a burnt fuse!
I would install the 400A one and call it good.
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I appreciate everyone on here.... I did install the 400A and everything is good with exception of my P0238-00 Turbo/supercharger boost sensor A - circuit high and P007D-00 Charge air cooler temperature sensor - Circuit high codes which I am hoping is just a disconnected wire from where I removed the supercharger prior to this issue. Before installing the 400A fuse I did do research on the junction box, fuse box just to make sure that application was compatible and it was.