Blyatsu vs CAN (WIP)

I decided to make a separate topic about my quest into making the canbus in my car work. I don’t think there will be a lot of people who will swap a 3SZ from a Sirion 2/Boon into an L7 (unless you feel like crying once in a while), but swapping the K3 from the same model will probably give you similar problems. In that case, it’s nice to have a topic like this to help you out.

Before we start:

  • I haven’t actually solved the issue yet, but when I do, I’ll put “FINISHED” or “SOLVED” or something like that in the title.
  • No, I’m not going for a standalone ECU
  • I’m also not going to use an older K3 ECU. I’d rather make this work properly
  • If you have any useful info or special knowledge, please reply to my other topic
  • Unlike my other topics, I’m just going to update and edit this post, instead of posting an update in a “reply”. Hopefully, in the end, I can turn this topic into a guide on how to solve the issue.


I’ll start with a bit of background info, and then work my way through all the info I’ve gathered so far.


In the summer of 2021, I swapped a 3SZ into my Cuore L7. At first I didn’t have the right key to ‘unlock the immobilizer’, but after I got that sorted out… a T-piece on the upper coolant hose exploded. But after sorting that out, the fuel filler hose kind of blew itself off, which resulted in me fueling up the ground. But, after sorting that out, there was a weird noise coming from the gearbox so we had to take everything out again. But that really was the last major issue (you can see where this is going). Although the car drove fine, the gauge cluster was lit with warning lights: brake warning, ABS, and a check engine light.


I used my OBDII scanner, which didn’t work at all. My first encounter with canbus: the DLC connector needs to be connected to HCAN and LCAN on the ECU. If it’s not, the OBDII scanner won’t work.

After running a pair of twisted wires from the DLC connector to the ECU, I was able to read the fault codes.

Which, ironically, told me there was an issue with the canbus (code U1000). I figured “well, it sucks that the CEL is always on, but at least it’s nothing major”. Or so I thought. In the following weeks, I didn’t really drive all that far, until I visited a some friends, about 90km’s away. FYI: I use my bicycle for daily commute and most other occasions, because I don’t have to leave the city that often. So a driving “far” to me is like 30+ minutes on the highway. Moving on.

Driving back home didn’t go so well…

So that’s were my quest began.
That speed signal should come from the ABS ECU through, you guessed it, canbus.

From the ABS ECU (on the left), up-and-over (because it’s a manual), through the gauge cluster, to the (EFI) ECU.


When I did the swap, I basically made the 3SZ work with the wiring harness I took from a YRV 1.3, which actually works quite well! However, that also meant using the ABS ECU from the YRV, which doesn’t incorporate canbus. I bought the 3SZ with a bunch of parts, including the ABS unit the car came with. I took out all the pins/wires that were fitted to the YRV’s ABS plug, and put them in the plug for the ‘new’ ABS unit (they have the same type of plug). One thing that I was struggling with during the ‘plugswap’ to fit the new ABS unit, was that I just couldn’t find the right page in the workshop manual.

The plug had three rows, but the manual showed just two.

It took some time to figure it out, but somehow I stumbled upon the answer when I was looking at second hand Sirion 2’s. The thing I noticed, was that all 3SZ Sirions had VSC (Vehicle Stability Control). In fact, only 3SZ Sirions had VSC. That’s why I couldn’t find it in this manual. It only covers the 1KR-FE and K3-VE.
For 3SZ-related stuff I used the Materia M4 manual. At first I wasn’t able to find it (because most Daihatsu manuals have a different layout), but, at last…

There it is!
After finding this, it was just a matter of putting all the pins in the right place.

Fortunately, the ABS unit seemed to work like it should (because it made a noise, so I suppose that’s a good thing), unfortunately, it didn’t solve the big problem.
I went to the junkyard (again) and got the ABS unit from a Sirion 2 1.3 (K3). As shown above, this unit didn’t have VSC, and the less complicated a part/system is, the less there is to mess up.


Although I haven’t fitted the new ABS unit yet, I just couldn’t wrap my head around the system. I was at a dead end, so I decided to learn more about canbus, starting with the basics


Picture it like a main road with two lanes, CAN high (red) and CAN low (blue), and smaller side roads (the nodes). The ABS unit is an example of a node, in this case. The white boxes on both ends are resistors (120 Ohm, for example), and are crucial for the system to function properly. Signals can bounce back within the bus, if there are no resistors. If you really want to understand how the system works, I suggest you watch a few video’s on YouTube, because it’s a bit more complex than just this picture. However, it was enough for me to wonder “where are those resistors?”. I couldn’t find anything about separate resistors, so I figured they had to be incorporated into one of the ‘canbus participants’.

I almost felt stupid when I figured it out, because I’ve used the same diagrams for many many many wiring harness related issues, but never noticed how the canbus itself is pictured in the diagram, including the resistors. But oh well, we learn as we go. I’m glad I figured it out in the end.

On the left you can see the main bus, with its nodes on the right

The two resistors are incorporated into the ECU and the ‘combination meter assembly’ (aka the gauge cluster). I don’t have the gauge cluster, and I think that’s the reason why my canbus doesn’t work.

That’s pretty much where I am now, and I’m going to find a way to either get a gauge cluster and see if that works, or see if I can make it work by using just a resistor. Once I’m done, I will update this topic and make a proper “how-to”.

UPDATE 1 - 12

I measured the resistance between CANH and CANL on the ABS plug, which was 124 Ohms (let’s say 120) . For me, this confirms that there is indeed one of two resistors missing.


very intrigued and looking forward to more and an eventual SOLVED. :slight_smile:

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Great post!.
I’m also in the middle of playing with CANBUS for 3SZ sirion as I’ve have installed Maxxecu Mini on that car.

For the terminating resistor, you could possible measure first and try to add if it does solve the networking issue.

For ABS, did you connect all four speed sensor to ABS ECU?

My suggestion is for you to get a proper Daihatsu scanner or a Toyota Techstream. For me I’m using Toyota Techstream, it allow you to diagnose the CAN bus and also access all system in the network i.e ABS , ECU and TCU.

The ECU is a manual transmission one right? Not Auto trans? If not it will be throwing code as both ECU & TCU also communicate to each other via Can bus

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Thank you!

Yes, that was exactly what I planned to do first. If it solves the problem, I don’t have to fiddle around with a second gauge cluster :joy:.

Only the front sensors are connected for now. It is the reason why the ABS light is on, but it’s enough to get a speed signal. I’m going to connect the rear sensors later.

I have thought about getting a proper scantool, but I’m still a bit uncertain whether or not I think it’s worth the investment. From what I could find, they are quite expensive.

And yes, I have a manual transmission (and also the ECU for a manual)


A while ago, I was searching for a DS-II scantool, and found out that they are quite expensive indeed. However, after reading your comment I searched for Techstream, which turned out to be quite easy to get. The thing I’m worried about is whether or not it will feature the right models? As it is Toyota only, you’d be looking for the Passo, bB or Rush, but if the software is meant for the US or Europe, that’s probably not going to help

Any way that you can contact the supplier of developer of the scan tool? They might just know if it also works. + If it doesn’t you can return is since it doesn’t provide what you asked.

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Re scan tools, if you have a spare laptop then these are fantastic tools for the money. I can confirm that mine communicates perfectly with my 2005 M100 Sirion, they have every make and model I have ever heard of, and many I haven’t heard of up to 2014

Its a clone of Delphi DS150 diagnostic software which is £4k of kit, plus about the same again per year to licence. This is a single payment of £30.

Mods - please remove if this contravenes rules, and apologies if so.


did you have any hassles with it hooking up to your car? meaning the plug fits?

Yep, worked fine. My car has a standard ODB2 socket - the usual isoceles trapesium shaped one. Identical to my 2001 Mercedes, 2004 Saab, 2004 Daewoo, and dozens of other cars I’ve used it on from years 1995 - 2013. You can buy a set of adapters for other cars, but I have never encountered a car with an OBD2 port thats not the normal size and shape.


Hi, do you have access to a scope? You could see how the signal looks. You can also measure the resistance between can high and can low, it should be 60 ohms, if one of the end Resistors is missing you’ll read about 120 ohms. If that’s the case, just install another 120 ohm resistor between can high and can low. The end resistors are important for the signal integrity, without them the data packets can be corrupted.

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Thanks everyone for the replies!

@Granger I will look into the scanner!

@Mick that was exactly what I was going to do! I don’t have a scope, but I was planning on measuring the bus to see if the resistance would be 120 Ohms instead of 60 (which would make sense since I have 1 of 2 resistors), but I wasn’t sure about measuring it with a multimeter. I don’t want to mess up my ECU because of the current sent from the multimeter. Can you confirm whether or not this is an issue?

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Measuring resistance between the CAN lines is ok, but measurements on other pins can do damage.

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Nope, you won’t detect the right vehicle as it is more for Toyota. However , as we know some toyota share with Daihatsu.
So for YRV and related i will select Toyota Duet in the Techstream. For sirioin you possible use Toyota Passo. However, for newer system you need to you Toyota Passo Sette. This is what i have been using for awhile and i manage to access all system from EFI, AT, ABS and more. Even the Can Bus.

DS-II is really expensive.