I read over this:

https://www.rx7club.com/3rd-generati...rolled-978049/

I have:

* All wheel speed sensors install
* ABS computer
* ABS unit

What I don't have is:

* Speedo sensor on OEM transmission. I am running a dog box race transmission and thus my speed is calculated via aftermarket wheel speed sensors that feed into the Haltech ECU.

I am worried that my ABS unit is likely not functioning because it doesn't know the vehicle speed and only knows the speed of each wheel.

Thoughts?

 

I posted the same question in the race race tech forum: https://www.rx7club.com/race-car-tec.../#post12572407

 

If you cant get the oem setup to work you can always look at the standalone e46 abs setup which is superior to our abs.

 

Starting multiple threads on the same topic is a good way to get a kick in your tea bags. Please don’t do that. It just creates excessive clutter.

Is the ABS warning light on?
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Yes, I'm aware. After posting here, I realize it maybe should have been on the race car tech forum since I'm missing oem bits. Opps.

No idea. I don't have the oem dash anymore. I have a haltech ic7. Do you think I should try to input oem light it into the ic7, so I can see on/off value?

Do you know if the oem abs needs vehicle speed input from the oem transmission to enable abs?

Thanks

 

Did some searching for you, this nice write up by arghx seems to indicate that vehicle speed is a parameter to determine how much slippage the ABS module should output to the hydraulic pump.

https://www.rx7club.com/3rd-generati...rolled-978049/



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Thank you.

I linked that same post in my original post.

I think you are right. The vehicle speed is an input to abs and I believe this vss is the one connected to the transmission.

If true, I have a non functional abs since I have a Jerico race transmission.

I should then just delete abs and move on with life. I'll save weight and easier bleeding.

 

Have you done a field test? A lot of ABS systems will run averaging or peak of non-locked wheel speeds for vehicle speed. I wouldn't rip it out until you have actually confirmed it. That description doesn't specifically say VSS output speed, the section above seems to suggest using all the wheel speeds if anything.

 

not sure how I missed your link, but I’ve done dumber things before and am becoming more blind by the day

I don’t know enough about the FD3 system to say, but I’d suspect the wiring changes/deletions more than a speed signal

 

you all fail, lol the 92-94 ABS uses the wheel sensors for speed. connection to the cluster is for the warning light

 

you can use this diagram and stick a light bulb where it is supposed to go on the instrument cluster. This is what i did when i was diagnosing my ABS issue. or even better you can use this as an input on the IC7 Dash.
Also our systems are similar. but i feed the wheel speed through the front wheel speed sensor but nothing in the ABS unit .

My ABS issue ended up being the control unit.

 

yeah I figured it was wheel sensors only. Back then these systems were pretty dumb. Nowadays they're more sophisticated.

 

Interesting! Good insights all. Ok, this is good news because I have yet to rip the system out. But, I was close. ha

Yes, as a next step, let me wire the ABS light into the ic7 as it would be good to know in general if I have an issue in the future.

I have a hypothesis about why my ABS is not working: I may have removed the ABS computer from the back of the car in the past without really knowing what it was. I probably thought "Why would anything important be back here? maybe this was for the radio system". lol

I need to figure out the harness connection and probably have to buy an ABS computer from EBay to get it back working.

Thanks all!

 

I have confirmed that my ABS computer is still installed. Phew.

Next up: I will be wiring the ABS light into the Haltech ic7 to see if it is complaining or not. Now that I think about it, before I switched over to the ic7, I had the OEM dash installed and the ABS light was not on. So, there is hope here folks!

I am building a power bleeder for my new Chase Bays manual brake master cylinder as I am having a hell of a time getting the ABS unit and everything else bled completely. Which is preventing me from trying to brake hard enough to activate ABS.

Stay tuned.

 

my light never came on with the faulty control unit. i did post my findings and the troubleshooting approach here 2001 rx7 in cyprus - Page 10 - RX7Club.com - Mazda RX7 Forum

 

I'm very curious about this I was planning to keep ABS on my DCT swapped car (it even dictated part of the turbo placement). Will be a shame if I made turbo fitment compromise if the ABS won't work haha.

 

I don't think I've heard of anyone switching to a manual master cylinder but keeping the original ABS system. It sounds like an interesting idea, please post updates if you get it working.

 

I have ABS intact still without vehicle speed input. It works fine

 

I just configured ABS is working! I got the Chase Bays manual brake master all bled and feels great. Easy to left foot brake.

For now, I have the high beam indicator set as the "abs error" light. I talked to Haltech this morning and they said a big software update is coming out that will allow me to change the entire setup and program any input to do whatever. I could have just flashed up a warning, but I did the high team icon for now since this is a race car and it is not street level.

Thanks everyone!

 

good thread to clarify it, thank you.
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