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Ok, made some progress (completely by accident).
I unplugged the battery to tack weld a larger resonator into the midpipe. Then went inside and made spaghetti and meatballs for dinner.
I hooked up the battery, determined to recheck the pinout with my cheat sheet(see above). Flipped the IG on and lo and behold, the damn ABS light turned on! And it stays on... So I jumpered TBS to GND, switched IG back on and viola! Got code 12 (one long, two short flashes) for LF wheel sensor. Unplugged the sensor and checked the resistance and it's open. So need to replace my junkyard sensor. I tried to see if I could get the pump to cycle in diag mode (by holding the brake and turning on IG), but guessing it won't work until I fix the sensor fault.
Only guess is the ABS module got pissed off as my wiring slowly progressed and it needed a reset. I started with the +12v from the engine fuse box, then I added the grounds, then I added the sensors, and finally I added the LEDs/sw12v/brake switch from the cabin. I'll have to turn it all on and jiggle everything and make sure there isn't an intermittent connection. I couldn't find the Bosch pins anywhere, so I had to use the ones that came with the connector I bought from ebay. I cut a short pigtail off on each pin and spliced every conductor together. Straightforward enough, but it did add 18 more junctions.
I found this list of NB2 ABS fault codes: ABS Diagnostic Procedure
There is no list in the NB2 ABS FSM.
In summary, if your pump isn't working, make spaghetti and meatballs and try disconnecting the battery.
Interesting. I wonder if we tried that, don't remember doing so but there were many fingers in that pie over the period I was troubleshooting. I see from post 3 that there are three 'hot at all times' wires, one of which goes through the brake switch, so your suggestion seems very worthwhile. Cat for you!
IME, yes, the unit will not cycle in diag mode unless you have erased all of the codes.
--Ian
I can confirm that the diag mode functions once the codes are fixed. In my case it worked after I replaced my LF speed sensor. I bled the brakes with my speed bleeders as usual and then triggered diag mode once with each bleeder closed and once with them open. I did them individually and didn't notice any air in the system and the pedal doesn't feel any different than w/o ABS.
I'd like to give an update about the NB2 ABS operation on track. This was at Mid Ohio last weekend on my TT6 car. I was running Toyo RR's in the damp/dry and Conti ECS in the wet. For reference the RR has less grip than a good 200TW and much less than the Hoosier R7. The ABS is really only useful in the wet or damp with unknown/changing grip levels. In which case it was pretty handy and rather confidence inspiring. However, I had it trigger a few times in the dry and it was unsettling. Once going into China beach (so about 115mph top speed there) and once over the crest into carousel. Every time it triggered caused me to completely blow the brake zone and thus the entire corner. The decel rate drops quite a lot when it engages and I just barely managed to keep it on the track. This was early on in the day and I hadn't pushed the brake marker too far, so I can see myself going off if I had been at 10/10th's. So I ended up turning it off in the dry using the handy switch I wired on the dash.
After talking with my buddy that races a 944 Turbo in TT3 (with the stock ABS), it functions very similar; if it engages then you've blown the corner, but it may save a tire from becoming square. So I may try to run the Friday practice at Gingerman and see if I can turn ABS on in the dry and manage to drive around the limitations or I just need to leave it off. It's definitely light years away from the modern ABS systems where you just push the pedal to the floor and let the ABS sort it all out.
I can confirm that the diag mode functions once the codes are fixed. In my case it worked after I replaced my LF speed sensor. I bled the brakes with my speed bleeders as usual and then triggered diag mode once with each bleeder closed and once with them open. I did them individually and didn't notice any air in the system and the pedal doesn't feel any different than w/o ABS.
I'd like to give an update about the NB2 ABS operation on track. This was at Mid Ohio last weekend on my TT6 car. I was running Toyo RR's in the damp/dry and Conti ECS in the wet. For reference the RR has less grip than a good 200TW and much less than the Hoosier R7. The ABS is really only useful in the wet or damp with unknown/changing grip levels. In which case it was pretty handy and rather confidence inspiring. However, I had it trigger a few times in the dry and it was unsettling. Once going into China beach (so about 115mph top speed there) and once over the crest into carousel. Every time it triggered caused me to completely blow the brake zone and thus the entire corner. The decel rate drops quite a lot when it engages and I just barely managed to keep it on the track. This was early on in the day and I hadn't pushed the brake marker too far, so I can see myself going off if I had been at 10/10th's. So I ended up turning it off in the dry using the handy switch I wired on the dash.
After talking with my buddy that races a 944 Turbo in TT3 (with the stock ABS), it functions very similar; if it engages then you've blown the corner, but it may save a tire from becoming square. So I may try to run the Friday practice at Gingerman and see if I can turn ABS on in the dry and manage to drive around the limitations or I just need to leave it off. It's definitely light years away from the modern ABS systems where you just push the pedal to the floor and let the ABS sort it all out.
This is another anecdote of normal NB2 abs triggering when not needed and causing a lack of braking power. We really need someone in this thread besides me to have used the MSM abs module. I realize is has the same part number from mazda if you re-order it but I never had this issue even on A7s, navalhawkeye can attest that I had the hardest stopping miata he's even been in by really just stomping on the pedal and letting the abs sort it out.
This is another anecdote of normal NB2 abs triggering when not needed and causing a lack of braking power. We really need someone in this thread besides me to have used the MSM abs module. I realize is has the same part number from mazda if you re-order it but I never had this issue even on A7s, navalhawkeye can attest that I had the hardest stopping miata he's even been in by really just stomping on the pedal and letting the abs sort it out.
My NB2 ABS did not do what engineerd2win's did. I would engage it on the track fairly frequently in the dry, with RRs, and it was what you'd expect for max braking. The rear end gets a little unstable at max braking into T2 at Laguna (130 down to 45 or so), but then my Miata doesn't have any aero.
Also, FWIW, I dunno what the "good 200 TWs" are these days, but the RRs on my Miata had more grip than the Rivals or RE-71Rs that I've used. I keep hearing about how fast modern 200 TW tires are, but that just doesn't match up with my experiences.
My NB2 ABS did not do what engineerd2win's did. I would engage it on the track fairly frequently in the dry, with RRs, and it was what you'd expect for max braking.
--Ian
I have retrofitted NB2 ABS onto my non ABS NB1 track car. I swapped the whole shebang, booster, master, lines, uprights,etc.
It also works as expected , ie like codrus experience and no issues like engineered2win had.
This is with aero and on A050s, the top of the tree R spec here in Oz.
Last edited by rascal; Sep 30, 2022 at 08:31 PM.
Reason: Typo
A couple photos of the rear ABS sender that I shot while swapping out a damage wheel stud:
Mounting this is why you need the ABS uprights -- the non-ABS ones (at least on my 99) are just rough castings where the sensor is supposed to bolt on, only the ABS uprights are machined properly.
--Ian
I ended up with two knuckles that don’t have the holes for the ABS harness. I have the ability to drill and tap the holes, but I am have the devil’s time trying to find the size and thread count of the two sensor bracket bolts and the single bolt for the upper bracket. Any change someone knows what the sizes of those two different bolts are? I am trying to keep it in line with what Mazda originally used. Thanks in advanced.
From memory, they take a 12mm socket. But who cares?! They don't HAVE to be any size, it's just a bolt to hold something on - too small, drill it out, too big use a washer.
That was very helpful. All three are M8x1.25 and your advice put me in the area i needed to be to match it. I am replacing the knuckle along with everything else in the rear as the car spent 6 winters in the north before it came south with us for its permanent home. The bolts are frozen and corroded. The first bolt head sheared right off when I tried to take it out (minimum force was used when it happened). After a complete replacement of the rear suspension, almost all of the corroded parts will be gone. Thanks again.
I just added abs to a non ABS car this winter. It wasn't as hard as some people make it out to be. In theory it is a very simple install, it's just very time consuming due to the volume of simple tasks that must be accomplished. If you want to talk to someone who actually has gone through with adding ABS to a Non-ABS car I will be more than happy to help you.
hey i recently bought another 2002 SE after my first one was totaled and noticed the newer one didn’t have ABS. Would you mind messaging me about the process you went through to adding ABS to your miata? I’m looking to swap the systems over from the salvaged one to the newer one
I have not actively wrote anything here but it has been my manual for my 2005 NB ABS into 1994 NA install. It has been quite a journey and the ABS is now in place but it does NOT perform as wanted.
The issues are:
•When ABS activates the brake-pedal sinks to the floor and the ABS takes over so the car brakes by itself for ~1second.
• The right front always locks up completely, even if i press very gently.
•The left front works very well with the ABS.
•Rear wheels brake very little and have no lockups or ABS activated.
•When the ABS is disconnected the brakes works ok, pedal does not sink. But still brakes hardest right front and locks it up.
My guess is air in the system and i am in the process of trying to get the air out by driving, bleeding, driving, bleeding. Using a computer to bleed does not work as i dont have OBD2.
Progress is slow, compared to non existent. Does anyone have any other ideas regarding what the issue might be except air. Or does anyone have a better idea to get the supposedly air out of the ABS.
•When ABS activates the brake-pedal sinks to the floor and the ABS takes over so the car brakes by itself for ~1second.
• The right front always locks up completely, even if i press very gently.
•The left front works very well with the ABS.
•Rear wheels brake very little and have no lockups or ABS activated.
•When the ABS is disconnected the brakes works ok, pedal does not sink. But still brakes hardest right front and locks it up.
My guess is air in the system and i am in the process of trying to get the air out by driving, bleeding, driving, bleeding. Using a computer to bleed does not work as i dont have OBD2.
Progress is slow, compared to non existent. Does anyone have any other ideas regarding what the issue might be except air. Or does anyone have a better idea to get the supposedly air out of the ABS.
The ABS doesn't care about OBD2. In the factory configuration it is wired to the diagnostic plug in the engine bay, but that's just convenient access to wires so that they can be grounded to send signals to it.
The first step I would take is to do the procedure in the factory service manual (FSM) to display any codes in the unit by flashing them out on the ABS light. That will tell you to ground a particular wire in the diagnostic connector, which is the one I mentioned above -- it's just an input wire to the ABS. Once you have displayed the codes you can clear them (another procedure in the FSM). Once you have cleared the codes you can run the self-test procedure (also in FSM).
A couple other things to check:
1) what does the car do if you pull the fuses for the ABS? It *should* behave exactly like a non-ABS car, if it does not then you have a hydraulic problem with the brakes. Perhaps one or more of the lines is clogged with debris or a problem with a caliper. How much of the donor system did you transplant? Was the brake system on the car fully working before you did the swap? Is it stock calipers or aftermarket ones?
2) Another thing to check is to make sure that you have all of the sensors wired correctly. AFAICT the orientation of the two wires for each sensor does not matter, but if you have accidentally swapped the wiring for two corners then it's going to do really bad things.
3) Also check to make sure that all of the hydraulic lines are routed correctly, including the prop valve. Swapping any of these around will also do bad things.
4) Do you have access to an oscilloscope? If so, then it's worth checking the waveform coming from each sensor to validate them. They should produce a speed-dependent AC waveform, where both amplitude and frequency change with wheel speed.
The ABS doesn't care about OBD2. In the factory configuration it is wired to the diagnostic plug in the engine bay, but that's just convenient access to wires so that they can be grounded to send signals to it.
The first step I would take is to do the procedure in the factory service manual (FSM) to display any codes in the unit by flashing them out on the ABS light. That will tell you to ground a particular wire in the diagnostic connector, which is the one I mentioned above -- it's just an input wire to the ABS. Once you have displayed the codes you can clear them (another procedure in the FSM). Once you have cleared the codes you can run the self-test procedure (also in FSM).
A couple other things to check:
1) what does the car do if you pull the fuses for the ABS? It *should* behave exactly like a non-ABS car, if it does not then you have a hydraulic problem with the brakes. Perhaps one or more of the lines is clogged with debris or a problem with a caliper. How much of the donor system did you transplant? Was the brake system on the car fully working before you did the swap? Is it stock calipers or aftermarket ones?
2) Another thing to check is to make sure that you have all of the sensors wired correctly. AFAICT the orientation of the two wires for each sensor does not matter, but if you have accidentally swapped the wiring for two corners then it's going to do really bad things.
3) Also check to make sure that all of the hydraulic lines are routed correctly, including the prop valve. Swapping any of these around will also do bad things.
4) Do you have access to an oscilloscope? If so, then it's worth checking the waveform coming from each sensor to validate them. They should produce a speed-dependent AC waveform, where both amplitude and frequency change with wheel speed.
--Ian
Hi Ian and thanks for your reply.
The brown diagnostic cable is not connected when i get the ABS to work. When i ground the brown cable the ABS flashes fault codes 5 short, 5 long, 1 short. I did try to clear these codes with the 10 brakes in 10 seconds according to the FSM but it does not seem to do anything.
When ABS is disabled the brake pedal does not sink but i would say there is still slight more brake power on the right front. All front brakes was changed at the same time to willwood aftermarket (disc and caliper). So the uneven braking might be explained by this.
regarding the sensors. They were checked today. According to the FSM the voltage was supposed to be between 0.5 and 2 when rotating the wheel once per second. I got 0.8 on front and 0.4 on the rears. The resistance front is 1650ohm and rears are 950ohm. When rotating front tires the resistance fluctuates between 1620-1680ohm. I dont have acces to a oscilloscope i am afraid.
Hydraulics lines are correctly wired and no leaks.
The conventional wisdom here was that these ABS units are bulletproof. Long story short ABS on my racecar would not work, everything suggested above and more was tried over 12 months or so, the local guru who had done ABS installs on non-ABS cars was stumpted, until I gave him another unit, plugged in the connector and it worked as scripted. In my case the problem was clearly in the electronic side, but the message is that if nothing else works, swap the unit.
I am also assuming that your self-test is working correctly - light comes on, then goes out (IIRC).
I have also been told copper pipe is a no-no for brake lines.
The brown diagnostic cable is not connected when i get the ABS to work. When i ground the brown cable the ABS flashes fault codes 5 short, 5 long, 1 short. I did try to clear these codes with the 10 brakes in 10 seconds according to the FSM but it does not seem to do anything.
When ABS is disabled the brake pedal does not sink but i would say there is still slight more brake power on the right front. All front brakes was changed at the same time to willwood aftermarket (disc and caliper). So the uneven braking might be explained by this.
regarding the sensors. They were checked today. According to the FSM the voltage was supposed to be between 0.5 and 2 when rotating the wheel once per second. I got 0.8 on front and 0.4 on the rears. The resistance front is 1650ohm and rears are 950ohm. When rotating front tires the resistance fluctuates between 1620-1680ohm. I dont have acces to a oscilloscope i am afraid.
Hydraulics lines are correctly wired and no leaks.
I would suggest repeating the code clearing procedure a few times and see if you can get it to take. My experience is that if there are codes in it then it will do not behave properly. If they won't clear then it's possible, as Gee Em says, that the unit is not working. These things are all 20+ years old and stuff doesn't last forever. If you can track down a list of the fault codes then it might be useful to look up the value that you're getting, but I don't have one.
Checking the sensors with a voltmeter won't tell you much, you really need to look at the waveform.
Sometimes you miss the key things in a long process….
The issue was simple and i found it out today. My pipes were connected wrongly. I switched MC2 with FR and now she brakes like a dream. All electronics work fine. Thanks for all help and good luck with your retrofits out there!
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