Vanagon – ecu failure and fix

First off, I’d like to thank the vanagon mailing list members for their outstanding support and help. They were right there beside me all the way.

List info here

Last Saturday as I was turning into the alley way that leads to my work ( doing plague induced alternate hours working) my van just died. No stumble, nothing.

Cranks fine, no start. I pushed van rest of way into work parking lot.

Then I started the diagnosis. Long story short, I found…

Fuel pump works key on

Ecu gets power key on

Coil gets power key on

Harness continuity to hall sensor and ground and power checks out fine

You get the idea, it all checked out. All the tests we would think of doing, including the Bentley manual ecu harness checks. Had work to do so that’s that for Saturday.

Sunday going over the same. Hall sensor failure was brought up. Well it was a candidate from the get go but I was putting that off. But I had to check if I was getting spark. Listmember suggested loosening distributor enough to raise it is shaft would turn and trigger hall sensor, watch for spark on grounded sparkplug. For some reason I was hesitant to do that but I was doing this alone and really needed to check spark. And I had no remote starter switch. I ended up with spark plug on case and video it when cranking. Yup,no spark.

Monday afternoon, evening. Back at it. Yes, the van still at work and I’m doing my evening shift. List member Geoffrey suggested brilliant idea of using timing light to determine if spark. I could cable tie trigger on and see the gun from drivers seat. No light flashing, No spark.

Swapped in a spare distributor. I had no idea if Hall sensor on it was good. But yet again no spark.

Tuesday, I took ecu out of its box, again. I had done that on the weekend to look for, oh, I don’t know what.

This time i found something. A bad solder joint on a power transistor middle leg. Bad enough that the leg would move in the joint. That must be it, I hoped. Mark and David on the list gave me hope that indeed it was the issue.

I reflowed the solder around that joint. Back up to work that late afternoon. Ecu in, and van starts. Not great, but starts.

I swapped the original distributor back in, and the van, after a bit of cranking, started. subsequent starting extremely snappy, much much better than before this event.

Poor pic of the bad joint, circled.

And in the other side of the board, the power transistor screwed to heat sink.

  1. #1 by syncro26 on April 1, 2020 - 12:59 pm

    Hi Alistair, I can’t believe you found and soldered that dry joint! Amazing and well spotted!



    • #2 by albell on April 1, 2020 - 1:04 pm

      Thanks John,

      But I missed the first time I looked at the board last sat or sun night.

      Was dry and loose. Pin could move. As some else said about it, it was probably walking wounded for a while.



    • #3 by albell on April 1, 2020 - 1:05 pm

      Oh and John, what with the goings on here and around the world and other things, I haven’t got back to you on the batteries, I will.



  2. #4 by pilZpeter on April 3, 2020 - 12:26 am

    oh yeah, once you are owner/operator of a vw t3 you’ll need a substitute. there is always something askew. close to home no problem, but in albania, bulgaria …
    here in austria just about every shop, restaurants etc. are closed. food markets, farmer’s markets are open for business.
    stay at home is the word.
    in my stack of: still to be read books i found ::: “shop class for soulcraft“ by matthew b. crawford. great reading! funny, ’cause last year i was in paris and visited Blitz Motorcycles.
    too many BMW’s for my taste, but the philosophy. great.

    • #5 by albell on April 3, 2020 - 12:39 am

      Hi peter,

      Here on lower Vancouver island there still is a definite feeling of “ it’s elsewhere” even though we are doing the right thing. Not as total a lockdown as in Europe though.

      Very strange times.

      Hope you keep safe, but let me know if you see any interesting T3 around.




  3. #6 by edbee on April 3, 2020 - 1:13 pm

    Hi Alistair,
    I’ll second John’s comment: “Amazing and well spotted!” And yes, strange times indeed.
    Best swishes,

    • #7 by albell on April 3, 2020 - 1:18 pm

      Hey Ed,

      I posted something about this on the samba, one guy had a look at his failed ecu and found same fault. Makes you wonder about how many failures are this one joint?

      And remember, I missed fault the first time I had a look at the board. Only on the second, desperate attempt did I find the problem. So it was perseverance over any skill 🙂



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