That is a bit dramatic I know, but its basically true. I went through a self service car wash last night only to find out that the drain underneath the cabin air filter was clogged. Everything got wet in there I got water in my passenger footwell and I also got water in the fuse panel on the right side kick panel.

I spent most of the morning drying out things and trying to run the heater with the engine management system faulting. Not fun. I continued to get a huge number of fault codes, most pointing directly to the ECU; engine management system, cruise control, parking brake. When I hooked up my obd II scanner I got almost a dozen power train faults - the cam position sensor, crank position sensor, and everything under the sun. Again this all pointed to the ECU, but when I pulled the plastic box for the cabin air filter and fresh air entry, the plugs for the ECU were dry and clean.

I disconnected the battery and remove the ECU wiring harness cleaned everything with contact cleaner and was still getting faults like crazy. I decided I needed to pull ECU and split it open to see what it looks like, and while tilting it to remove it a whole bunch of water came running directly out of the aluminum housing. Not good. I had a blow dryer handy, and when I split the box to look at the circuit board I was surprised to see it looked perfect AND had some type of plastic laminate over all components and the board itself. That was a nice thing to see as there looked to be no damage even though the board was energised multiple times and the car run at least a dozen time with water covering the board.

I dried it some more with a blow dryer to make sure there was no moisture anywhere, and upon reassembly the car started and ran perfect. The only fault said to set the parking brake manually with foot on the brake, so I did, and when I put it in gear all faults were clear.

I seriously dodged a bullet here, and feel very lucky. I also will be checking my drains often so I never get hit like this again. I advise all x350 owners who haven't determined the status of that drain to check ot out. Just pull the access cover on the right side cowl cover where the cabin air filter is, remove the filter and look toward the fender for a half moon shaped opening or a screen - I see little tabs sticking up around the drain that look like they are for a screen, but mine was missing. grrrr. That's ok: I am still joyous that I am not shopping an ECU and figuring out who will program it for me!

 

Glad to know the car is OK. I regularly check the plenum drains because I was forewarned on these things by owning a Rover 75 before the Jaguar. This car had the ECU in the plenum chamber so if it blocked up the ECU could end up sitting in a pool of water. Not good !! However it never happened to me, but I carried on this caution with the Jaguar.

 

Thanks for the report, Blairware. Good advice for all Jaguar owners!

Since the circuit board in the ECM is coated to protect it from moisture, I assume your fault codes were caused by water shorting the connector pins where they are exposed between the connector and circuit board. Is that what you would conclude?

Cheers,

Don

 

Hi Guys,
I know this is an old thread, but the same scenario and same symptoms from a car wash in my wife's 04 XJ8 I am unclear if the best access to remove ECU is from the firewall in through pollen filter, or removing glove box. I'm not afraid to take this on, just needing some how to's from the well of wisdom here.
Thanks,
Dave

 

Hi Dave,

You access the electrical connector for the ECM under the pollen filter housing in the engine compartment, but the ECM itself mounts on the interior side of the bulkhead/firewall, behind the glove box. I would recommend accessing the electrical connector first to check for signs of water ingress, then removing the ECM only if it appears you need to check its internals.

To disconnect the electrical connector, you will need the correct size 5-point security star bit, which is like a standard Torx bit, but it has only 5 lobes instead of 6, plus it has a hole drilled in the center to seat over a pin in the recess on the screw that fastens the connector to the ECM. I bought a set of 5-point security/tamper-proof bits on eBay for less than $20.

The hardest part is getting the pollen filter housing out. The instructions are in the Workshop Manual, but you don't have to remove the windshield wiper or entire windshield cowl/trim. Just remove the enough fasteners at the right end to be able to move the trim out of your way.

Cheers,

Don

 

Thanks Don. Can you tell me what is involved in taking the ECU out from behind the glove box? Just don't want to do anymore disassembly than is necessary.
Thanks big time,
Dave

 

Hi Dave,

I think the instructions for disconnecting the glove box have been posted in this forum. It's not difficult, but you may actually be able to access the ECM without removing the glove box. The ECM sits in a bracket and I can't recall if it just pulled out or was secured in some way. You can see the ECM in this photo to the right of the blower fan housing:




If you find that you will need to remove the glove box in order to access the ECM, don't bother disconnecting the electrical connectors on the glove box. The wires are long enough that you can just rest the box on the floor.

Cheers,

Don

 

So Don B. In removing the ECM do you still have to take out the Pollen Filter stuff to release the connections if you take off the glove box?

 

You do need remove the pollen filter to access the ECM connector security screw. But I suppose it might be possible to pull the ECM and its connector through the firewall and then disconnect the connector. But my memory is that the electrical connector has a weather seal that is larger than the openings for the connectors on the ECM and might prevent the harness connector from pulling through the firewall. The connector is secured to the ECM by the 5-point tamper-proof Torx screw, which is accessed from the engine bay side.

If anyone else reading this has pulled the ECM and its connector into the passenger compartment, we'd all love to hear about it.

Cheers,

Don

 

The ECM in my '05 Super V8 fried after a trip through the car wash. The pollen filter compartment filled with water, because the drain holes were blocked with leaf debris. After going through the car wash, I pulled onto the street. Water poured from my glove box area onto the floor on the passenger side and my car stalled in the middle of the street. I called a tow truck to take it to the shop. Turns out I had to replace the ECM with a NEW one from Jaguar Merriam Parts, $1850, after discount. Nobody I could find re-manufactures or rebuilds those particular ECMs. None were found in the salvage yards. My independent Jag repair shop charged $600 labor to replace and configure the new one. Was an expensive car wash at $2450!

Believe it or not, this story had a happy ending. The comprehensive part of my full coverage auto insurance policy paid for all of it in full...even the towing! How lucky can you get!

I do know my shop went through the engine compartment to replace it. They also had to repair a couple of connector pins. Checking for debris is now part of regular maintenance!

Cheers!

Jon

 

Sad to read this thread only now... same for me on a 2004 X350 3.0 , a nice trip to the carwash and before getting out of the washing tunnel, I had plenty of fault messages and the XJ was only driving on first gear with no effect from accelerator and iddle at 1800 rpm... There was water on passenger floor and the cabin filter was completely soaked... of course I found a clogged drain just in front of it.on outer side of cabin filter housing. I removed and dried the ECU printed circuit but with no effect.... JLR official dealer doesnt want my car in as they dont do "older cars" ... now the car has been towed into a classic cars specialist and I'll try an "plug and play" exchange unit from cartech uk ...

 

Chiming in since I removed my ECU this past Saturday. My 2008 XJ has a newer ECU which does not have the security torx bolt on the ECU harness. It seems the ECU was updated in 2006 or 2007, to part # 6R83-14C568-CA

The drain beneath my pollen filter was clogged, resulting in a wet ECU. I have a replacement on order & will update next week when I try programming the new one. I removed the 2x 10 mm nuts from the engine bay, and a T27 bolt securing the ECU beneath the glovebox. The ECU came out through the passenger footwell
ECU for 2006-2009 cars. No mounting hole for the security bit as seen on 2004-2005 ECU


2004-2005 ECU. Note the single piece connector interface and threaded hole for a security fastener.


jag·uar
ˈjaɡˌwär,ˈjaɡˌyo͞oər
nounA large, heavily built cat that fears water

 

guess we all need to go outside and check the status of our drains . Debris from Live Oak trees Fills mine up several times a year .

 

Yessir. It's a frustrating problem in the first place. I thought I was in the clear since I checked my sunroof drains last summer.

 

A few of us in the uk have bonded a fine mesh under the slats in the scuttle,looks good and reduces ingress of debris

 

I guess some folks have it bad enough that the ECU gets fried. Before replacing it, it's worth cracking open the box and giving it a proper drying out. I just wanted to mention that as mine had a multiple ignition/run events and it was perfect. I suspect that getting it out within 12 hours of the event helped as well.

One forum member left the water in the ECU for months as he tried this and that in spite of my advice to just get it out and dry it. It's been over 6 years since this happened to me, and I'm on a newer X350 these days,, but for those wondering how to remove it,, I recall it was a struggle but not each shattering.

I removed the plastic over the cowl, and the plastic box that the cabin air filter sits in (where the drain clogs) then I think I cam-levered the electric harness off from that side. There is no security bolt on late 2005/early 2006 cars with the first update cycle- referred internally as X356. When the connections were dry I almost gave it up.. Then I removed the carpeting UNDER the glove compartment- I did not remove the glovebox itself, just worked behind it, but removal may help shed some light on the situation. Once I pulled it through into the interior, I tilted it and a stream of water ran out. I was not confident it could be saved at that point. I then asked if I could use my blow dryer at the store I had parked in front of the night before next to the car wash.

As I say, getting the water out may have been my saving grace, and doing it before the water had time to damage the unit - even after energizing the ignition and running the car at least a dozen times.

Don; Do we have a sticky on this, or is it part of the "What you need to know" post? I think it needs to be even if most people end up in here after the event.

Stay save and keep that cabin air filter drain clear!

 

I have edited the title of this thread to help search engines find it and I have made it a Sticky.

Thanks for the suggestion, Blairware!

Cheers,

Don

 

Agreed! I did the hair dryer, too, after taking my photos. Unfortunately, my misfire still remained upon re-installation. Fortuantely a replacement was only $60 on ebay... delivering this afternoon, so I'll attempt reprogramming & share results. I am hopeful that's the only issue - either way, I'll post an update

 

New ECU did the trick I'll try & post some screenshots for navigating SDD. My big tips would be to:
1) Have your car AND laptop on power supply while connected to SDD
2) Run a diagnostic session with your original computer, THEN export the session. This preserves the original VID block while letting you communicate with the other modules. When you install the new computer, manually enter the VIN at the start page and import your old session
3) Attempt the Read VID Block test to see if you have good connection before attempting to reprogram. Better to find out you can't connect now!

 

Seeing as this thread occasional re-surfaces from the annals, I feel no shame in giving it a bump back up for review.

If I am reading everything correctly, the circuit board was treated against water, but the implicit cause seems like the connector housing allows water to pass through which in turn shorts the circuitry by way of the pins.

Presuming the pins are in fact the weak link, how about a healthy dose of dielectric grease across the pins and connectors?

Am I missing something here?

Naturally, apologies in advance if this was already discussed. And at the same time, if this was already solved (aside from keeping the drain holes clear), we could all benefit by way of updating the sticky.