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How to start reading ECUs

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  • How to start reading ECUs

    Okay, so big topic here and I know I'm well out of my depth at the moment, but I'm really trying to get some work done on my car so I figured why not dip my toes in.

    I have a Honda Odyssey and I'm looking to do some engine swappy, superchargey stuff but Hondata don't make a mod for my ECU, and while I know I can piggyback a Haltech Elite into my car to do everything I want there, I'm just wondering how the hell people even reflash ECU's in the first place. What equipment do they use to read them and how can I start decoding mine in order to read the CAN-BUS and start mapping my ECU?

    If you're a big nerdy then I wanna talk to you. I have some programming experience and tiny tiny understanding of electronics but I've managed to get by so far so I'd really REALLY like to even begin to understand what's going on inside my little grey box.

    Thanks in advance for people's patience and if you're also interested please tag in with a 'following'!

  • #2

    But my understanding of it is this:

    from what I know about computers, sometimes it's a lot of trial and error if you're starting from scratch. For example you need to know what chip your ECU has and where you'd expect it to "dump" data. You may need to apply power to a specific pin on the chip for a precise period of time in order for the chip to dump it's memory which you can then read.

    You'd then get a massive binary to reverse engineer, then you'd need to work out what areas of memory the data goes into and what their values are.

    However what I think happens is someone works out how the dealer software works, and uses that to extract data. After all the manufacturer knows exactly where the data goes on the ECU so the info is already there. That leaves you will values to play with knowing where they go and what effect they'll have.

    I did a little bit of 4.4 motronic when I had a volvo and that was mega difficult - but it's unique to the Volvo 850. Most ECU's these days share processors like the Bosch ME9 etc will all be relatively common to each other - obviously it's had some upgrades in 20 years but you get the drift.

    You could maybe send an email to Haltech? I'm sure one of them would tell you how ECU read/write works.

    I know for a fact though, that Alientech have capability to read an Odyssey ECU with K-Tag, in fact you can do it with Kessv2 through the OBD port so you don't even need to take the ECU out. tools and mapping is expensive shit though - because it's difficult and time consuming.
    I stripped my car out so much it now has 49/49 weight distribution.

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    • #3
      Thanks mate!

      I figured it's gonna be a ****tonne of hex snooping etc and chip-matching but I've no idea where to even start. Was thinking of getting an ECU from a wrecker and start probing it etc.
      When it comes to that K-Tag business, I had a look and the website only supports the RB1-2 but not the RB3-4. I'm hopeful as this is the first time I've seen an ECU site support the Japanese ECU's at all lol, but yeah looks like it's serious business with the chip probing adapters and shit!

      Will definitely keep it in mind though man, thank you so much for the lead!