Disaster - a "fried" ECU!

[tyro]

I thought that I would add this story about my recent disaster as it might be of interest to others on this forum!

My car is a 2006 Octavia 1.9 pd tdi Estate (BKC engine) which has given me sterling service and never let me down once in 110,000 miles - until last week!

After an uneventful 40 mile trip, the engine suddenly "died" with no power whatsoever and initial attempts to start it were unsuccessful. Now, as my engine failed, I did notice that the oil pressure warning light came on despite the fact that the engine was still turning with the transmission (before I declutched) and I also noticed that the temperature gauge had dropped to zero. Once I had rolled to the side of the road, I noticed a strange noise from the engine compartment and, when I lifted the bonnet I found (the key by now having been removed from the ignition) that the radiator cooling fan was doing strange things - idling slowly then speeding up to full speed then slowing down again - while I could also hear a clicking sound (like a relay) coming from the fusebox next to the battery. Having just returned from a business meeting, wearing a smart suit and the weather being wet and windy, I did not feel inclined to delve into the electrics at this point.

Attempts to restart the engine were futile - the engine spun healthily on the starter but would not fire. I cannot recall whether or not the engine management light was lit or not. However, after a wait of about 15 minutes, I tried again and the engine started rather lumpily and this time the eml was lit. I then managed to limp (just) to my local independent garage after which the engine died and would not restart.

Needless to say, the garage people were rather flummoxed by all this but (at my suggestion too) they did check for water in the engine fusebox as well as checking for blown fuses, bad connections and bad earths, all to no avail. They then sought the advice of an auto electrician who finally found the cause of the problem - a failed ECU. I gather that failed ECUs are quite rare in these cars but I'm enclosing a couple of photographs which I took of the "motherboard" or "printed circuit board" of the ECU once the auto electrician had opened it up - the red arrows point to the area of "mischief":

http://i1339.photobucket.com/albums/o713/circumstantial/IMG_1991pointersmalljpg_zpsdac0d96a.jpg:original

http://i1339.photobu...ce.jpg:original

Looking at the whole unit, it looks to me as though there are no obviously failed "components" as such on the pcb, just two or three "fried" connections and, if you look at this image -

http://i1339.photobu...1f.jpg:original -

it appears to me as though the "fried" joints are where pins 76 and 77 (and maybe also 54 and 55) join to the pcb. Any idea what other bits and pieces those connections go to?

Obviously I am going to be faced with a substantial bill but I thought that others might be interested in the symptoms of this sudden failure as well as the "post mortem" findings too! One concern I have is what exactly might have been the cause of this failure - was it most likely just a "dry" soldered joint which had built up resistance then failed - or was the cause some "external" problem such as a failed relay or short circuit or something like that which burned out this part of the ECU?

Funnily enough, it had crossed my mind that if the auto electrician can't find a replacement or rebuilt unit, it might just be an idea to try repairing those soldered joints myself - I have done it (successfully) in the past on radios and suchlike!

Edited 25 March, 2013 by tyro

[donovan]

Has ecu ever been opened before? That has been caused probably by water damage. Question is how. Most likely wiring loom to ecu had water damage or similar. I would check wiring to ecu first then see what other side of ecu looks like as it may be worse than you think with possible processer damage

[tyro]

Sorry, but I'm not sure if the three pictures which I added to my last message displayed properly - I'll have another go!

i1339.photobucket.com/albums/o713/circumstantial/IMG_1991pointersmalljpg_zpsdac0d96a.jpg:original

i1339.photobucket.com/albums/o713/circumstantial/IMG_2000pointersmalljpg_zps1a8ea4ce.jpg:original

i1339.photobucket.com/albums/o713/circumstantial/VAG_EDC16U1_zps8772721f.jpg:original

[shark_90]

That's a rare occurence.

I can't find anything with a quick look in the wiring diagrams that creates a circuit between the pins you've suggested, I could tell with the ECU here though.

If we can get the ECU running on the bench then we will be able to get your immobiliser data from it and supply you with a used replacement ECU at much less than the price of a new one, if that helps. I'm quite sure we have at least 1 in stock.

[tyro]

Hello Donovan,

Thank you for your reply!

First of all, I'm not really au fait with adding pictures on this forum and I wasn't really sure about what I was doing - I started up a PhotoBucket account just so I could upload those pictures - surely there must be an easier way?

Anyway, to the ECU. No, this ECU has never been opened up before. There is also no sign whatever of water ingress into it and both sides of the pcb look totally pristine with the exception of the "fried" or "burned" area around those three or four pins which I have pointed out in the pictures.

But, at the end of the day, I just thought I would post this as it might be of interest to some people particularly as ECU failure does not, apparently, affect these cars that often. I am pretty well resigned to an expensive bill!

Perhaps I should just stick to my other car which doesn't have such crazy complicated electrics -

- very easily fixed with a penknife and a ball of string but not quite so fast and not quite so efficient on fuel!

Kind Regards,

John.

Edited 25 March, 2013 by tyro

[tyro]

Thank you, shark_90, for your quick reply.

I shall certainly keep you in mind but, at the moment, I think that the auto electrician in already researching means of either having the unit rebuilt or sourcing another unit to have the immoboiliser data transferred to it.

Kind Regards,

John.

[rwbaldwin]

It looks like a failure on the internal layers of the board. IIRC, pin-76 is a sensor ground. All the external wires in that area are really thin (0.35) so they are not a cause of what is a high current short.

[tyro]

Thank you, rwbaldwin, for your reply!

Well, that information is very useful and reassuring to know because, from what you say, it sounds as though this is a failure which has "just happened" due to a failure of the board itself and most likely not due to any "external" causes such as a short circuit.

Kind Regards,

John.

Edited 25 March, 2013 by tyro

[silver1011]

First of all, I'm not really au fait with adding pictures on this forum and I wasn't really sure about what I was doing - I started up a PhotoBucket account just so I could upload those pictures - surely there must be an easier way?

When viewing the pictures in Photobucket there will be a link titled 'direct link'.

Paste this into the box that opens in your post when you click the 'Image' box just below the smiley face...

[tyro]

When viewing the pictures in Photobucket there will be a link titled 'direct link'.

Paste this into the box that opens in your post when you click the 'Image' box just below the smiley face...

Thank you, silver 1011! I shall bear that in mind next time I want to upload images!

Kind Regards,

John.

[Stormchaser]

This is a really rare occurance and i hope you sort it out.Good luck

[Stuart_J]

Perhaps I should just stick to my other car which doesn't have such crazy complicated electrics -

- very easily fixed with a penknife and a ball of string but not quite so fast and not quite so efficient on fuel!

Kind Regards,

John.

Thats lovelly, looking at the piccie Im also reminded what a sunny day looks like.

[o_ptic]

From the look of the failure it could be water ingress. I'd also be tempted to try a patch up of the board.

Looks like from the photos there are several pick up points that you could solder onto as a temp measure! It may not work but worth a try as you've got nothing to lose!