Alright question for my big wigs. Due to all the random issues from car i decided to do some poking around. In my poking i took the trunk right wheel well cover off in the trunk and started checking wires from rear fuse to battery to harness. This is what i discovered. So the top right terminal metal bar that crosses over to lower terminal coming from batter and trunk fuse box connected is loose and fried. Not bolt loose but like broken and free where it meets the 250A fuse. melted the plastic and a little of the cable and is all corroded. Out of curiosity i ran the car walked back there wiggled it around and nothing happened. But i did get quite a burn as it gets very hot which explains the plastic. Could it be getting hot because it’s broken? I’d say not because it must of blew or malfunctioned causing it to get hot now. Is it supposed to be a 400A dude like the one above it? Has anyone EVER seen this on this car or others? I’m leaving the plastic off due to how how it gets but any ideas on why this is happening ? I will try to source a new fuse but what could cause this. Thanks guys.

 

The whole junction block must be replaced after the draw is found.

Here is a link to the MY2003 Electrical Guide:

https://www.dropbox.com/s/1ocfmq0ivw...Guide.pdf?dl=0

Many of the main circuits are the same after the facelift.

 

Here is the post facelift Electrical Guide, which is the correct one for your vehicle:

https://www.dropbox.com/s/x3ksf8ird8...006on.pdf?dl=0

 

Or if you do not want to use dropbox here is a direct link to a pdf:

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

Mellow

 

Looking at your pics, it would appear that cable crimp has failed. A loose or corroded crimp has extra resistance, which heats up due to normal current flow.

If you look closely at that cable terminal end, can you tell which end got hotter? Does it appear the heat originated at the crimp and moved towards the fuse block? Or does the fuse end appear hotter, and the heat transferred toward the crimp? If the fuse end was the source of the heat, that was probably not caused by the fuse itself, but the bolted connection. From the little bit I can see, it looks like the heat originated at the crimp.

Don't drive the car like this. That is totally abnormal to see such heat damage. It will continue to get worse. That cable feeds the front power distribution box. The biggest fuse there is 50A, but most are in the 20A range. If the draw was caused by a fault downstream of the front power distribution box, even the biggest fuse there would have opened first, long before any damage would occur back by the megafuse. It wouldn't hurt to inspect the front power distribution box for any signs of heat damage, just to be safe.

As previously mentioned, you'll have to replace that entire fuse block assembly. You'll have to splice in a new section of cable, too.

 

Thanks to everyone and you! Now my local junkyard has plenty of the blocks but this being the supercharged variant of the car are they different? They all look identical just of course some with fuses where they should and shouldn’t be. Also can i use and 250 amp mega fuse? there’s a lot of options as long of course as they have the right terminal connection? As to your heat transfer questions. I couldn’t tell. I know with car on or ignition on the bolt even gets hot clamping to fuse as well as the cable. It’s hard to tell which hatched first causing what. I tried to use all logical thought but can’t pinpoint it i have the general knowledge on how current flows work of course. Is it possible if everything checks out the block may not have to be replaced ??? Just splice a new cable and new fuse?? Thank you again

 

That block is toast. Replace it.

No idea about differences between models for the megafuse block. I would think they're all the same for a given year. Match the existing fuse rating.

 

Looking at your pics some more, it appears you've got two megafuse holders side by side. I had initially thought it was one big unit, but it's more of a modular design. Take a look at this, from Littelfuse:

https://www.littelfuse.com/products/...981001zxt.aspx






If that is correct, these megafuse holders are readily available from many sources. You don't have to buy the expensive Jaguar version. Here's one example on eBay, complete with a 250A fuse. Seller says he ships worldwide, not sure where you are located:

https://www.ebay.com/itm/LITTLEFUSE-....c100005.m1851


Got to thinking a bit more about possible causes of the overheat. Perhaps the heavy cable between the megafuse and the front power distribution box is lightly contacting ground, creating a not-quite-direct short circuit. Had it been a direct short, amperage would have exceeded 250 and that megafuse should have blown. Maybe it was only 249, or just enough to find the weakest spot in the cable run. If so, here's what I suggest. As previously mentioned, replace the megafuse and holder, and splice in a new section of cable. When you first connect the battery, don't tighten the clamp right away. Observe if you get a big spark as you make contact. It's normal to get a light spark, but not a heavy one. If that happens, quickly disconnect the battery cable and investigate further.

 

Okay so i have done everything. I replaced the 250 amp fuse and the plastic block encasing it. Got a new crimp to cable spliced the original cable past the point of corrosion and crimped it together. I didn’t not replace the block reason being i pulled it checked all connections all voltage with meter traced with electrical guide and everything checked out even fuses. The mega fuse was completely blown in half the terminal pulled right out of it. I reconnected slowly and lightly and got no spark what so ever as i had battery unplugged as should be. When connected normal relay clicked and everything was fine. I went to ignition turned the key to second position before start everything came on nicely. Ran to the back and touched my new connections. NO HEAT. Started car let run. NO HEAT. Before i was idling at 5/600. had misfires abs codes gear box codes dcs codes the whole 9. They are gone as for right now and the car idles 800 healthy!!! All gas seemed like to check out. Thank you all again.



One question. Could this fuse cause any ignition coil, plug, injector, or sky misfires what so ever? or would that be power to engine fuse compartment. They do trace one way or another just wondering if it could be possible.

 

Cylinder misfires **

 

Oh yeah, it's very possible. That burnt connection was obviously continuing to consume power, as it was getting hot. That means less energy available downstream, i.e. reduced voltage. Some systems are monitored for correct input voltage and will flag a corresponding code if out of range, but not all systems are like that. You'd also have a weaker spark, erroneous sensor readings, etc.

However, keep in mind the computer is back in relearning mode because you had the battery disconnected. Several drive cycles may be required before certain faults reappear. Continue monitoring it and see what happens.

 

800 sounds too high so may be it's running OL (open loop) - should rapidly go CL (closed loop). You should see this in the status (via OBD).

Continued running OL will run rich (so poor MPG) and gradually damage the cats.

 

Hey Jag!! You were the first i came into contact with when i got this car with the dropped valve seat. All of that is nice and fixed and she’s idling where she normally is 650/700 it seems. i always thought that was too low most cars being at 800. My new/old issue is these damn misfires. I’ve done almost everything. New plugs new coils traced harness everything. The same cylinders 1,3,7 then i’ll get a random even numbered cylinder here and there. I’m so close to getting this cat where she needs to be after so much money, blood, sweat, and tears that i’ve wanted to cry lol. So today i read a code i thought i knew and it makes sense. P0355 The ignition coil or coils are responsible for igniting the air/fuel mixture inside the combustion chambers. ... Code P0355indicates there's an electrical problem in either the primary ( the computer side ) or the secondary ( the spark plug side ) of the Ignition Coil "E" Circuit. Is my ecu bad? nothing i’m doing is helping. Nor do i know if that fuse blew with the previous owner or while i had it. Fixing the fuse stopped all the random faults all at once gearbox abs dcs parking brake cruise control everyyyyything and i couldn’t start the car. it’s all good now car is back driving. But these misfires are killing me. I have studied the electrical guide thank you to previous posters!!! You all are great as always. Tomorrow i plan to pull ecu and i guess trace more wire and multimeter? The ignition specifically. my compression is 120 across the board and 100 in the cylinder that dropped the seat. I added restore in the engine so it should bump it up but i don’t believe its enough to cause misfire. My injectors are also well and fuel filter clean. Any ideas ?? Anyone seen this?

 

Also i constantly drive with a scanner hooked up to get all my trims and i had an overheating problem before it was mainly to monitor temps because i know better than to trust the gauge. There’s no in between. it’s either just right or dangerous lol. So my trim status should be closed? The scanner is the Scan Gauge 2.

 

also i know you’re going to say something about the compression. My buddy has an 04 str and it’s the same. Is that normal or okay for a 9:1? So far i’ve seen 120 being the normal even with wet testing. What are yours ? I only mention this because the factory page don’t remember which one says this car should have a 160 or higher compression which i find hard to believe ..