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[TheBoy]

In HVAC, got a B11ED-87 Electric Heater Control Module

Is that an axe PTC heater to help warm cabin until engine warms?  Looks too much of a bugger to change if that has gone faulty.

Schems show it's powered via a 150A fuse, but I can't find a 150A in the usual fuseboxes?  Schems are Part 2 under HVAC in Topix's wiring diagrams.  Any idea where this fuse could be, as worth checking before going further?

[YZ250]

Stumbled across this:

The source was Jaginfo.org

‘The megafuse is in the battery junction box in the boot on later cars. It’s 150 amps.’

No idea if it applies to yours or not. 

Although that may be for the XE, XF, and not the XJ. 

[YZ250]

It’s a bolt in fuse, apparently in the trunk side BJB, not a normal blade type.    That info was in reference to the XJ X351, so you probably know all of this. 

Schematics shows Battery, to Battery Junction Box (150A Fuse) , PTC + going to Heater Electric Booster.

[TheBoy]

Yup, cheers YZ, thats what I'd found in the schematics, but it doesn't say where it is.  I'm making an assumption that a Battery Junction Box is near the battery, much like the fusebox on to of the battery's +ve terminal on an Omega.  XJ has nothing like that, and the access panels in the trim in the boot only give access to microblade type fuses.

[YZ250]

Yup, cheers YZ, thats what I'd found in the schematics, but it doesn't say where it is.  I'm making an assumption that a Battery Junction Box is near the battery, much like the fusebox on to of the battery's +ve terminal on an Omega.  XJ has nothing like that, and the access panels in the trim in the boot only give access to microblade type fuses.

Yes, I’d agree with your assumption that you should be able to just follow the battery +ve lead to the closed cover junction box close by. 
Hope you manage to find it. 

[TheBoy]

If I have to start taking the side trims out, that becomes a weekend job.  Same if it's behind the rear seat backs (where there is a shit load of technical stuff)

[Doctor Gollum]

If I have to start taking the side trims out, that becomes a weekend job.  Same if it's behind the rear seat backs (where there is a shit load of technical stuff)

Sounds like the Jaaag engineering team needs to spend time poking around a W221 to see how to make things accessible.

Merc put everything behind the rear bulkhead. 4 T25 screws, and 10 push pins and the boot is stripped. Hardest part of working in there is reaching from the rear bumper and getting back out of the boot after doing the work

[TheBoy]

Boot trims are easy enough once the boot is emptied, aside from the scuff plate that has to come off.  If I was being kind, I'd say age has made the bits brittle, and the 4 clips that hold it once the 3 screws are removed are strong little fikcers, and something normally breaks.  Only I'm not going to be kind and say the same setup which is on hers is equally prone to damage (and looking at 2nd hand ones on ebay for hers shows they have all broken on at least 1 of the 4 clip holders.


Rear seats are brilliant to take out, aside from 2 problems....    ....having a decent specced variant means the number of plugs you have to unplug blind, with the weight of the seats on your arms, and the fact you can't remove the rear head restraints without removing seat base, then tilting seat back at enough of an angle.  All doable, but a faff without an assistant.


In general, I think Jags are better designed than Mercs - but then so is a Ford Focus - but parts quality and production shortcuts let them down badly.  Not that Merc have great parts quality if Bro's succession of S Classes is anything to go by, but I guess all marques are constantly looking to drive down costs from their suppliers.

[TheBoy]

Not that it matters for those seeking advice on Jag forums, as the standard answer is take it to a dealer.  Or for the yankee forums, take it to a shop.

As I'm sure Kevin Wood and Lord Opti can attest to

[TheBoy]

Found it (I think)


The 150A fuse has 12V both sides, so assume it's OK?

[Kevin Wood]

Have you got a current clamp meter?

That would tell you if it's working.

[TheBoy]

Have you got a current clamp meter?

That would tell you if it's working.

I'll have to get it back of Gixer, though not sure if it did DC.


I was kinda just trying to sort all the niggles out, making sure everything worked, and had got to the point of going through the faultcodes.  If this was an easy fix, then I'd do it just so everything is working. If it needs that heating element replaced, I'll wear a jacket for the first 2 or 3 miles

It stems from how infrequently I use the car, then when I took it to Cornwall last month, I began to notice a few things that annoyed me, mostly around sticky soft touch coating - I thought I'd done them all, but found several I missed, lol.  So when I got back, I made an effort to sort everything, including the soft touch....   ....then at the weekend, noted I'd missed the memory buttons on the doors, lol.

[Doctor Gollum]

Zero soft touch on The Proper Car... All the switch gear is actual aluminium or piano black.

Exception may be the steering wheel buttons, but after cleaning these when I bought the car, they're still spotless.

All the issues and foibles you have with that car, it makes you wonder why Jaaag thought they could get away with it and why you bought one... Although given your family allergies regarding Mercedes you probably didn't have alot of choice

[TheBoy]

The soft touch coating on a 2010 car is inexcusable.  That said, the design is pretty good, and not just a parts bin scattergun approach as used by your favourite since the early 90s.  Sadly all let down my occasionally poor manufacturing and some really crap parts from their suppliers that they really need to get on top of.

That said, mine has been pretty good aside from wheel and tyres.  Though 99% of that is due to the local councils wasting their money on new headquarters and shite, rather than spending it on what they are supposed to.

Her Jaaaaggg has a constant problem with corrosion on fixings.  Not sure if that is an XE problem,. or if hers was just parked in the North Sea most of its life.  Not heard Kevin Wood grumble about that, so assume that's unique to hers.

[TheBoy]

Although given your family allergies regarding Mercedes you probably didn't have alot of choice

Family allergies?  One of my bro's loved 'em, right up until the point of that eureka moment, and never had another.  One of my other bros got an awful lot of work from Mercedes, when they'd send him a chassis, the Bilstein catalogue, a shit load of money, and a remit of getting it to go around a corner without falling over.  He left that company after deciding that some turds just can't be shined.