ABS replacement - RX8Club.com

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ABS replacement

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Old 05-24-2018, 09:13 PM
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ABS replacement

Replaced my ABS unit with a used one. The ABS block was faulty. I realize normal procedure is to reprogram the ECU to communicate with the replacement ABS in which only a dealer can do. I was wondering if I swap the module from the original ABS into the used one, would it now communicate. By doing this I could save the cost of sending the car to dealer to reprogram. Anyone know of any reason this would not work.

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Old 05-30-2018, 09:11 AM
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jayh, first of all, please specify: do you have a DSC? If not, there's no need to reprogram anything. For USDM RX-8's w/o DSC Mazda has only one as-built data, so ABS units are interchangeable between years and cars with different options.


In case, You have a DSC.
In this case You need to be sure a new unit will have the same as-built data programmed in it. I've made a research on different ABS and ABS/DSC units and can tell that first generation of USDM RX-8s have 4 different as-built data:
FFFF FFFF FF24 (ALL, NO DSC)
8081 4200 FF6B (2004-2005, 4port, 4AT, DSC)
1081 4200 FFFB (2006-2008, 6port, 6AT, DSC)
4081 4200 FF2B (2004-2008, 6port, 6MT, DSC)
So as you can see, they differ only between engines and transmissions. For DSC there's only 3 as-built data calibrations. Although they are reprogrammable.
So, your way is:
- take DSC unit from the vehicle with the same engine and transmission and just replace your's with it
OR
- take the cheapest ABS/DSC unit from whatever RX8 you can find, replace yours with it and reprogram as-built data.
To reprogram as-built you need a FORScan software (it is free to use) and a cheap ELM327 adapter.


PS. If you have already replaced your ABS or ABS/DSC unit and all is working fine and you have no errors (ABS or DSC lights don't come up and there's no DTC error codes in diagnostics) - you do not need to reprogram anything. You need to reprogram as-built data only in case there's a DTC C1805 (mismatched PCM and/or ABS/TCS module) and ABS or DSC lights glow.

Last edited by EmiteR; 05-30-2018 at 09:13 AM.
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Old 05-30-2018, 12:31 PM
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Fantastic info EmiteR.

Thanks for posting this.
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Old 05-30-2018, 08:39 PM
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Thanks informative post with that said I will just try and reinstall the module
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Old 06-07-2018, 09:03 AM
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EmiteR, thank you so much. It was my understanding that their is also VIN coding involved with the ABS control module, it wont communicate with just any car. To the best of your knowledge, will rewriting the as built data erase the VIN match?
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Old 06-07-2018, 12:57 PM
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BigBadChris, afaik there's no VIN in ABS/DSC units at all. They only communicate with ECU, SAS and cluster by sending and receiving only real time data via CAN. I didn't find any initialization sequences of CAN messages between ECU and ABS/DSC when I was reverse engineering RX-8's CAN bus.
The only information that is checked by ABS/DSC unit is activation message sent by ECU. This message is static and has only several least bits valuable. These bits bring constant value which depends only from AsBuilt. Like 0b00000010 for european standart power modification and 0b00000100 for high power. So there is no way VIN is sent to ABS/DSC unit - it can't just fit into 1 byte of data.


As I've already told, there are few ways to change ABS/DSC units:
- buy unit from a vehicle with the same engine (4port or 6port) and transmission (MT, 4AT, 6AT) used in yours. You can verify it via VIN also (if you have the VIN of vehicle ABS/DSC unit is removed from):
go to https://www.motorcraftservice.com/AsBuilt type your VIN and press submit. Of VIN is correct you will see complete AsBuilt for your car. The only data you need for ABS/DSC is instruction for the module 28-01 in "BCE Modules". Then do the same with VIN from vehicle that donored ABS/DSC unit for you. If instructions match then you can easily replace modules without any software work.

- buy ANY ABS/DSC unit and reprogram it's AsBuilt data. Now you know from previous point how to get instructions for ABS/DSC unit by your VIN. Install the unit you bought into the car, take the latest version of FORScan with extended license (also freeware, requires only registration on FORScan forum and filling request form with some info about you), a cheap ELM327 adapter (USB is better choice than bluetooth) and program these instructions into ABS/DSC unit for 2 minutes (1 minute from that 2 is for celebrating the success ) from menu "Configuration and programming". That's all. If all's done correctly, clear DTC's, disconnect, restart the car and you'll have ABS/DSC working in your car.
And no, reprogramming AsBuilt data/instructions to ABS/DSC will not cause any VIN erase in your ECU (if I correctly understood your question)

Last edited by EmiteR; 06-07-2018 at 01:05 PM.
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Old 06-07-2018, 02:22 PM
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Very good, thanks. I was told from the automatic to manual swap thread that there was an ECU pairing issue. It sounds like this is really different as built data. I did the swap a year ago but continue to get a DSC light. I am willing to bet that my As Built data is not right.



I will be attempting to reprogram my unit as soon as I receive the ELM327 adapter.
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Old 06-07-2018, 02:33 PM
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Can you please share me your current config? I mean, engine and transmission. Did you change the ECU for MT one or did you reprogram yours to use with MT? If ECU was changed, can you please share it's VIN and your original VIN? I'll check the easiest way for you to fix the issue.
Few more questions: is there the only DSC light or ABS one is fired up too? What DTC codes are present in diagnostics?
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Old 06-07-2018, 03:40 PM
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I pulled a 6 port, 6 speed manual trans ECU from a donor car. The dealer was kind enough to reprogram my keys to the new ECU, and they thought they would "help" by flashing the chassis VIN into the donor ECU.


Chassis VIN JM1FE17N850152747



Donor car VIN VIN JM1FE173850161138


I have no ABS warning light, only a DSC light. No check engine light and no codes present.
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Old 06-07-2018, 04:05 PM
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Ok, just checked. You had a 4AT in your car and DSC (ABD instruction 8081 4200 FF6B). You installed a powerplant with ECU from the vehicle that also had a DSC (ABD instruction 4081 4200 FF2B). So there should not be any issues, you just need to reprogram your ABS/DSC unit with ABD instructions suitable for donor ECU ABD (4081 4200 FF2B).
But this will work only in case dealer changed only VIN and didn't harm ABD in donor ECU.


Please try to reprogram ABD like I suggested and let me know. I'm gathering info about RX-8's electronics and software, any result of your operation will be very useful for me.
As you can see from my profile I'm from Ukraine and that means I have no possibility to work with USDM RX-8s. I know only 3 8s imported from USA to Ukraine (and they all are far from me to work closely), so can't gather enough info about different modifications. For european 8s that trick with ABS/DSC ABD works flawlessly, hope it will work also for US 8s.

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Old 06-07-2018, 04:10 PM
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I appreciate your diligence in helping me, especially considering you dont have access to the car. I will be happy to share any information I have. Just so I understand, the as built data is included with FORscan?

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Old 06-07-2018, 05:00 PM
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No. FORscan is the software to work with Ford and Mazda. What's new
This is non commercial project under GNU license or something like that. These guys are making really great job of research and development and let everybody use their product for free. But unfortunately they are not able to gather, analyze and process all the as-built data for all Fords and Mazdas. So FORscan is just a powerful tool to work with your Mazda or Ford, if you know what you're doing. But if you don't - so you can easily shoot your Mazda's leg Just kidding. There's nothing that can't be rolled back.



What about ABD. This information is provided by car manufacturer. For Mazda/Ford it is free and easily requestable from the site I have posted few posts above. It is a huge mass of bytes understandable only by car modules. In other words this is the set of instructions for all vehicle modules to understand each other.
In your case your RX-8's ABS/DSC has ABD instruction to communicate with AT ECM+TCM. You need to put there instruction for communicate with MT ECU. It is: 4081 4200 FF2B
Only this you need to put there, nothing else. Another thousand of strings is for other modules.
As soon as you get your ELM327 adapter - just let me know and I'll try to do my best to help you reprogramming your DSC unit.
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Old 06-07-2018, 05:02 PM
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Got it, thanks!
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Old 06-11-2018, 09:52 PM
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An update. Went to see my buddy who has the dongle and FORscan. We were able to read and write the as built data, but had no luck making the DSC lights go away. We confirmed that the original ABS unit had the 4 port At as built data, and flashed it to the provided six port MT data. We also tried a second ABS unit and confirmed it was also six port MT data. That unit triggered an ABS mismatch DTC code.

EmiteR, appreciate your time and help. I welcome any additional input you may have.
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Old 06-12-2018, 02:48 AM
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Sounds like more than ABS/DSC issue...
Did you read DTC error codes before reflash? Were there any? If yes than what exactly?
What instrument cluster do you use in your 8? Is it original AT one, or have you installed IC from the donor vehicle?
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Old 06-12-2018, 08:36 AM
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It’s the original AT cluster because mileage data is stored in the cluster, and I didn’t want to put five thousand extra miles on the car. You did mention the cluster talks to the ABS. The codes in the ABS were c1805 (Mismtached ABS / PCM according to internet). When I tried the original DSC, the car got even more unhappy and showed codes for front right wheel speed sensor. C1233 and C1234. I guess I need to try again and swap the cluster?
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Old 06-12-2018, 10:46 AM
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Yes, cluster can be the issue.
Let's make things more clear with DTCs:
- were there any DTC errors after swap and before any actions with reflashing as-built data in your DSC?
- were there any DTC errors after reflashing your DSC and before connecting second MT DSC?
- where there any DTC except ABS-PCM mismatch after connecting second MT DSC?
- do both front ABS sensors present in car and are they ok? may be the wiring/harness issue?

I start thinking that dealer has changed as-built data in your PCM to as-built that matches your chassis VIN to make cluster work. If I'm right that gonna take a freight train of elbow grease to fix.
First of all, you need to check your actual as-built data in PCM. Unfortunately, FORScan doesn't allow you to do that. But I know how to do that without visiting the dealer and using expensive software.
There's a great guy JamieM from British RX-8 club who has developed a small script that enables cruise control option for european 8s that don't have it enabled from factory. Beside enabling cruise control, this script reads all PCM as-built data and outputs it to console. So you can use this script just to read as-built. It's safe and won't make any changes or break anything in your car. Here is the link to JamieM's topic on british RX-8 club with full how to instructions:
https://www.rx8ownersclub.co.uk/foru...p?f=30&t=74833
Refer that and share me your current as-built data.
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Old 06-12-2018, 11:26 AM
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Oh, nevermind my previous post about reading PCM as built data. JamieM's script shows only calibration part which is the same for both your chassis and donor VINs
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Old 11-15-2018, 03:06 AM
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Originally Posted by EmiteR View Post
No. FORscan is the software to work with Ford and Mazda. What's new
This is non commercial project under GNU license or something like that. These guys are making really great job of research and development and let everybody use their product for free. But unfortunately they are not able to gather, analyze and process all the as-built data for all Fords and Mazdas. So FORscan is just a powerful tool to work with your Mazda or Ford, if you know what you're doing. But if you don't - so you can easily shoot your Mazda's leg Just kidding. There's nothing that can't be rolled back.



What about ABD. This information is provided by car manufacturer. For Mazda/Ford it is free and easily requestable from the site I have posted few posts above. It is a huge mass of bytes understandable only by car modules. In other words this is the set of instructions for all vehicle modules to understand each other.
In your case your RX-8's ABS/DSC has ABD instruction to communicate with AT ECM+TCM. You need to put there instruction for communicate with MT ECU. It is: 4081 4200 FF2B
Only this you need to put there, nothing else. Another thousand of strings is for other modules.
As soon as you get your ELM327 adapter - just let me know and I'll try to do my best to help you reprogramming your DSC unit.
Hi, I see you are extremely knowledgeable about this subject my 05 rx8 4sp AT is at dealership right now, I put new ECU/PCM new TCM and new ABS pump/Electrical unit because mine was continuously running. Now I don't have the donor car VIN# for any of these parts and they all came from different donor cars but the part numbers where given to me by Mazda dealership so there all the stock parts and correct parts. Is the dealership going to be able to reprogram the TCM PCM/ECU and ABS to work with each other. God I hope so, please help me with anything you can. Also are there any other systems such as cruise control or power steering that need to be programmed into the new ECU/PCM . Thanks .
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