Cooked ECU

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Originally Posted by djam1

That I do
I should be able to retire by selling them

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I hope your not planning on retiring anytime in the next few decades...

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Originally Posted by BBS Guy

i guess someone must be the devils advocate and as such i must point out that TD5 ECU's are not exactly well known for self destructing.

We would all feel really bad if whatever destroyed your old ECU destroyed your new replacement.

As such i would advise that you still follow all advice in respect of checking possible problems that the many fine members of this board have advised.

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I did raise this with Brad at KLR and we have checked the harness for oil and it's pretty good. It has had a replacement "modified" harness though Brad said they end up needing replacement anyway? Not sure about the other faults, hopefully there's no underlining cause that we don't know about...

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Originally Posted by djam1

Maybe its getting a bit more common?
How curious! said Alice "exploding ECUs; whatever will they invent next?" - Land Rover Zone

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Pulled the cover off the ECU and it is the exact same component that has failed in mine! I presume that it might be designed as a fusable resistor that is designed to fail, also the SMD transistor next to it seems to have gone as well. No silkscreen on the board to identify things.

Going to send it off to Paul, hopefully useful to him. Cheers

Matt

Hi Matt,

It should still be useful, thanks.

It looks like there is a fairly large scorched section on the board. My guess is one of the output drivers has failed first, and the resistor is just collateral damage.

cheers
Paul

Matt's ECU turned up in the mail today and I was a bit curious so see if I could find evidence of why it failed.

Matt says that the ECU was in it's current state when he bought the Deefer.

The first thing I noticed was that the ECU has been swimming at some point:
https://www.aulro.com/afvb/images/im...013/09/372.jpg

The back side shows that the water/mud had splashed over one (possibly two) of the six vent holes on the back of the ECU:

https://www.aulro.com/afvb/images/im...013/09/373.jpg

The inside of the base shows that mud, and most likely water had entered the ECU housing:

https://www.aulro.com/afvb/images/im...013/09/374.jpg

This isn't a great shot but you can see a white residue between the circuit board and case in a couple of places. The residue completely spans the gap in one place. I'm assuming these residues are salts and minerals left behind when water evaporated. You can also see a burnt patch just to the left of centre where an additional resistor has failed.

https://www.aulro.com/afvb/images/im...013/09/375.jpg

The blown underside resistor is connected to the hexfet transistor with the purple paint dot. You might be able to make out the while residue on the circuit board connecting the three legs of the transistor. My guess is the residue may have provided a leakage path for current which has eventually caused the resistors to fail.

https://www.aulro.com/afvb/images/im...013/09/376.jpg

The worst damage is under the resistor/zero ohm link on the topside. The board is burnt and one pad has come loose from the surface, although there is still continuity with a nearby via.

I suspect the moral is that water and electronics don't play nicely. If you go swimming with your Td5 you need to take precautions to ensure the ECU isn't submerged. Sealing the vent holes on the back might be a good idea too.

cheers
Paul