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I've done lots of research and haven't found a solution. I figured it might be time to post on here.
The primary goal here is to capture and log individual wheel speeds using the existing sensors.
Two ways this can be accomplished.
Pulling a physically signal/voltage off each component
Reading the CAN protocol off the ABS or ACD unit. (over my head, but most ideal if someone has done it)
Basic background to what I've already uncovered.
The ACD can be setup in two different ways. This focus will be with ABS unit.
The ABS sensors are feed into the ABS ECU and the ABS ECU sends a 2.2v Hall signal to the ACD ECU. (per my research)
Since I'm not a electronics expert, I didn't want to just tap into the wires and see what happens.
I'm just not sure if splicing into these wires (Like TPS signal) will cause issue. (burn up an ECU input or cause an incorrect signal)?
I'm also not sure if this would be considered a digital signal or an analog signal? Has anyone on here had any ideas?
Thats not quite clicking as Im scrolling through the schematic. The schematic you posted shows ABS input to ACD coming from ABS ECU Pins 18,20,21,32 with ABS Wheel Speed Sensors on Pins 6,8,22,30. But if you look in the ACD (w/o AYC) section its getting fed directly from the wheel speed sensors (and you can see the pullups and grounding done in the ECU).
Are there 2 functionally different ACD Computers with one reading some unknown signal from ABS ECU and the other processing the VR signal?
I did do some research on how to read wheel speed and it is a bit tricky to not mess with the ACD or ABS Ecus because there's something about matching the input impedance (there's a thread on LancerReg IIRC) on a pullup and then setting the switchover point of the digital signal to a specific value. This is off memory so I don't recall the values.
Alternatively, you can use a VR signal conditioner that buffers the signal (signal upstream not effected by signal downstream basically) and will convert the VR signal into in a square wave with varying frequency. I happen to have a pair of the Speeduino VR conditioning boards I was going to wire up this winter but I decided to go for option 3.
Option 3, Motec with ACD control will just run a harness from the ACD connector (harness side) to the Motec ECU for logging and controlling all of it.
Here is where it gets confusing and lets just stick to the US non AYC setup. There are two ways to setup the US ACD without AYC. The non ABS setup is how you stated. The ABS only has 5 wires that directly come from the ABS ECU. All the ABS sensors go to the ABS ECU. I see how it can get confusing. I didn't understand this until I rewired the whole car.
Here is my pin out, Plug C-139. You can see that 19-20-21-22 is not pined.
Here is MoTec Pin out for the ACD controller. Which I think you are looking at.
So it appears it's sending a 2.2v Hall signal to the ACD ECU. I'm not able to build a VR signal conditioner. That's above my knowledge base.
It would be easiest to go to the MoTec MDC. However, I'm a bit disappointed in it after playing with it. I really don't like how MoTec doesn't use any steering angle strategy (if they do, it's not tune-able) . The OEM ACD ECU seems to be much more advanced and I'd prefer to keep my reflashed OEM ACD ECU.
Thats not quite clicking as Im scrolling through the schematic. The schematic you posted shows ABS input to ACD coming from ABS ECU Pins 18,20,21,32 with ABS Wheel Speed Sensors on Pins 6,8,22,30. But if you look in the ACD (w/o AYC) section its getting fed directly from the wheel speed sensors (and you can see the pullups and grounding done in the ECU).
This is only for the cars without ABS... For cars with ABS the signals from the wheel speed sensors go first into the abs and then are passed trough to ACD ecu
I presume that the individual wheel speeds that you can log from the OE ACD ecu dont have the high enough sample rate?
Even if the sample rate isn't high enough, it's really better than nothing. I really don't want to add more ABS sensors.
Down the line, I'd like to look at Bosch motorsports ABS. I just can't stomach the $8,000.00 at this time. The MoTech MDC control was my go to.. However, there is little to no information on them. When I played with the software, I couldn't believe they don't use steering wheel angle as a map. Maybe it's not as big of a deal as one would think. I've been playing around with the ACD ECU Flash software and I'm impressed by the OEM setup. Plus I have the English racing ACD tune. I highly recommend.
Mike you should shoot Mike over at Pro Awe a message about this. Their evo doesn't have ACD but I know they log individual wheel speed already so maybe he has some insight he can share about it.
My car doesn't have ACD so I'm not sure how the ABS and ACD send/receive signals but worse case scenario you could bypass the ABS module for data collection purposes and make a harness that pulls the signals from the sensors and sends them to an IO channel as well as the ACD.
Even if the sample rate isn't high enough, it's really better than nothing. I really don't want to add more ABS sensors.
Down the line, I'd like to look at Bosch motorsports ABS. I just can't stomach the $8,000.00 at this time. The MoTech MDC control was my go to.. However, there is little to no information on them. When I played with the software, I couldn't believe they don't use steering wheel angle as a map. Maybe it's not as big of a deal as one would think. I've been playing around with the ACD ECU Flash software and I'm impressed by the OEM setup. Plus I have the English racing ACD tune. I highly recommend.
I was looking for that unit awhile back, where'd you find it at?
Mike you should shoot Mike over at Pro Awe a message about this. Their evo doesn't have ACD but I know they log individual wheel speed already so maybe he has some insight he can share about it.
My car doesn't have ACD so I'm not sure how the ABS and ACD send/receive signals but worse case scenario you could bypass the ABS module for data collection purposes and make a harness that pulls the signals from the sensors and sends them to an IO channel as well as the ACD.
I've PM him about this a while back and he doesn't know. You can easily log speed sensors when you don't have ABS or ACD. The complicated part is sneaking a signal and not upsetting the ACD ECU. I know the ACD and ABS units transmit a CAN protocol, but it seems like no one knows how to read it outside of evoscan.
What makes you think there's a CAN protocol between those modules? It'd be extremely odd for Mitsu to have CAN communication between those two modules and nothing else on the car. Easy evidence is usually the presence of a twisted pair of wires.
My guess is that they're likely talking over the MUT protocol somehow. One of the more tech savvy guys might be able to look into that.
What makes you think there's a CAN protocol between those modules? It'd be extremely odd for Mitsu to have CAN communication between those two modules and nothing else on the car. Easy evidence is usually the presence of a twisted pair of wires.
My guess is that they're likely talking over the MUT protocol somehow. One of the more tech savvy guys might be able to look into that.
That's the hope and why I posted. I don't even mind sending funds their way. There has to be a way to make all this work.
considering the way the ACD ecu is wired in the non abs versions of the car my guess is that the abs unit just passes trough the individual wheel speed sensor signal. No CAN on that car and I doubt it is any sort of mut protocol...
I know I'm bring this back from the dead. I'm know able to confirm that you can log wheel speed if you splice into the wires above. I am now able to log individual wheel speeds and do not receive any ACD or ABS errors. You will need to use a digital input without a pull up.
I know I'm bring this back from the dead. I'm know able to confirm that you can log wheel speed if you splice into the wires above. I am now able to log individual wheel speeds and do not receive any ACD or ABS errors. You will need to use a digital input without a pull up.
Bit of a shame i missed this thread as i could have helped you with all of this haha.
I removed my ABS computer and re routed the wires directly into the ACD ecu. The biggest headache was getting the ABS > ACD health check wire correct. The ABS ECU sends out a small voltage signal to the ACD ECU constantly to remind it its working. Without this input the ACD ECU Faults. Fun times.
Can also confirm the wires go into the ABS ecu on certain pins and then come out the ABS ECU on different pins which then continue on to the ACD ECU. As for the comms side i believe it uses MUT to communicate.
Do u guys really find that much time playing around with ACD computers? ive just stuck with my ralliart ACD ECU for ages. I do have my stock one i could reflash just never looked into it
Dec 20, 2020, 04:24 AM
