ABS Module Repair
 

Ok, here is how I repaired my ABS Module.
This is not a DIY or even a troubleshooting thread, because this whole procedure is very risky and could easily lead to irreparable damage to the ABS module, death or dismemberment.

You've been warned!

Background:

I have an 04 RX8. After purchasing it and driving it for a while I started getting the ABS/Parking Brake/DCS trifecta. So I did a lot of troubleshooting, and I fixed the steering angle sensor wiring which also fixed an intermittent PS issue.
After a while I was able to pin down the exact situation which caused the intermittent fault.

After driving the car until the engine bay was good and hot I could shut down the engine and immediately restart and the trifecta would appear within the first 50ft of driving. This first 50ft or so after starting the engine corresponds to ABS self check.

I could also trigger the lights if I triggered ABS/DSC with the engine bay hot. (Yes I could lock my brakes up)

If I started the car cold then in the first 50ft the lights would all clear, so it was definitely some sort of thermal effect.

When I had the tools to read the fault codes I got were ABS pump continuity and Steering angle sensor. I don't have the numbers offhand.


So I scoured the net looking for similar problems and found the BMW guys with a Bosch 5.7 ABS (looks almost identical to ours) who had similar intermittent problems.
removing "snot-like" goo from ABS circuit board- Bluebee pls. read! - Bimmerfest - BMW Forums

The source of many of our problems are some silver wires that are ultrasonically welded to a gold pad. If thermal expansion/contraction stresses the weld enough it breaks and then only has continuity under specific circumstances, like when the engine is cold.



The Fixes:

New ABS unit- Expensive to buy, it has to be calibrated to the ECU (or more to the point the ECU is locked to the ABS serial number) by the dealership (for $$$).
Used ABS Unit- Relatively cheap to buy because it has to be calibrated to the ECU, and might already have the issue.
Professional repair - Not a bad idea, there are places that will do the fix on BMW ABS modules for under $200. I haven't found one that does our units, but I didn't spend that much time looking/calling. Might be promising.

I didn't really like any of these options. So I tried an experimental solution.


The Solution:

The wires can't be soldered, but they can be glued and instead of removing all the gel I used it to my advantage.
First I got some wire glue in a syringe. This stuff is used to repair traces on circuit boards and the flexible plastic of display leads. I didn't go with the epoxy because that would require mixing the two parts then loading a syringe with it and that seemed like too much hassle.
Then I removed the ABS module from the car and carefully cut the housing along the edge with a razor. Do not let the blade slip in very far or it could damage the internals. It will take multiple passes and the bottom won't be accessible. I found that when three sides were done and I tried to lift it the bottom side snapped cleanly.

Once it's open you'll see the brain of your ABS. Be VERY careful, I tried nudging the silver wires with a screwdriver (to make sure they were firmly attached) and in the process a couple of them lifted off their pads the ultrasonic welding process is far from strong. The gold wires are so thin I had a lot of trouble seeing them with my bare eyes, and I've heard that they are so fragile that touching them can break them. I just stayed clear of them and hoped for the best.

At this point I took the syringe and applied the conductive glue to the exposed silver wires on the gold pads. This gave me a feel for the applicator and also ensured they were bonded to their pads (including the ones that I broke off.)

Once the exposed silver wires were glued I used the syringe to put a little wire glue on the pads encapsulated in the gel. I started by inserting the syringe and trying to put a dab in the silicone gel on the pad, but by the end I was using the syringe more to make a hole and then pack it with the glue. The two important points here are to not disturb the gold wires and to not create a short between wires.

The space is very tight, and a sure hand is a must. As you can see I got a little messy, and by the time I was done I was very worried I'd ruined my broken ABS unit. I'd recommend try to be as precise as possible with the easy ones then work your way in.

After gluing all the silver wire pads I used electrical tape to reseal the module and re-installed. I'd love to say that this is a permanent fix, but I don't know. I've been tracing this intermittent fault for quite a while now, and it's had me fooled before. Right now all I can say for sure is that the fault is cleared (and I tried to bring it in), I didn't break it worse (I'd count that as a major win), and I'll keep you guys posted!

Interesting..

A brand new ABS Module for all Series RX-8's does not require Initialization at a Mazda Dealer (MMDS -IDS), it is plug and play.

Using a Used ABS unit is a different matter.

Hmmm, I had mine replaced under my extended warranty and the Mazda dealer charge my warranty company like $2400.00 with a extra charge for programming it. It was a brand new unit. Mine died when my alternator overcharged, boiled my battery, and killed a few other electrical components a few years back.

Nice write up.
Im currently on my 3rd ABS module now, I found out that my old LS2 esmerill coils was dead, and caused my ABS control unit to get fried when I tried to start the engine. I got the fault code C1186 both times it happened, Tried a lot of things and opened up the cover to check the gold and silver wires with a macro lens attached to my dslr, damn those wires are small! but i couldn't see anything detached.
My fix was to get a used abs module from ebay(only about 100$) and have it programmed at a mazda dealer (charged 300$).
But since I was stupid enough to connect the ls2 coils one last time to check them my abs module died again with the same fault code. got a new unit from ebay and plugged it in and now I only have the ABS mismatch code, haven't bothered to get it reprogrammed yet. I think I might will try to swap over the electrical relay unit stuff (marked with red in picture) in the abs from the new to the old and see if that clears the code, then I don't need to go to dealer.

Those are MOSFETs. One is for the pump the other I'm not sure about. Let me know if you figure out how to remove them without damage, I poked and prodded a bit but chickened out. If that is your issue then it might be a easy fix or you could destroy it in the attempt.

I have actually desoldered/cut the pins the mosfet unit and inspected it, but i didn't figure what was wrong or how it worked but there was no physical connection problems. but one of the mosfets could be fried. I just clipped all the pins to get it off and soldered them together when putting in back together, it was easy. So I will try this again today but this time I will swap the working on over to my ABS module with the fault code, since that is already paired to the PCM. I will let you know if it works

Get the serials/take pictures. They should be easy enough to test with a multi meter once you know exactly what they are.

There is no need to get into the mosfets, I just swap the whole unit assembly. I have got them out now and did a test without soldering them on first and there was no abs or dsc lights in the dash. Will soldier them back on and do some test driving to be sure its permanent later.
Here is picture of the units remove from the module.
Http://www.rx8club.com/attachment.ph...1&d=1408819246

Works perfect! all warning lights off, all dtcs gone :D
So this is a easy fix for ABS relay/power issues. You could also replace the mosfets/IC stuff on the orignal unit but thats a little bit more complicated. I should have done this the first time and I would have saved 300$ in reprogramming.

Nice! Now take the bad ones off their heat sinks so we can see serials.

Yes I will do that, hope we can source the components then I can fix the two other ABS modules and sell them cheap ;-)

https://www.rx8club.com/attachment.p...1&d=1408915901
Found some parts online which seems to be correct: S2V70_2K, MBR2545CT

3 fets and a schottky diode. The diode is pretty common, but I can't find a datasheet on the FETs yet. Once I find a datasheet we should be able to find some cheap off the shelf replacements. They are all TO-220 so nothing too oddball.

which of the two to you think failed? I put my money on the S2V70, 3>1

They are N Channel Mosfets. This guy used 75N06 as replacement.
ItaliaAuto ? View topic - Tech FAQ - Common 156/147 symptoms and causes

They are about $2 a piece. Just like the diode. Should bring the cost of repair to $8 if you just changed everything.

Yeah the Mosfet is the likely suspect probably shorted when it got surged.

interesting find. I replaced 4 ABS for other guys 8 last year with a used good module, 5th one is coming up and it's a S2 8, it seems like these ABS module are prone to fail (10 yrs design life?)

Looks like I can collect those old ones, fix it, and use it again. :)

Just an update. I have had no ABS trouble since my repair and I've been exercising traction control quite a bit. The wire glue is holding and has fixed all prior continuity issues.

what size are the torx bits for removing just the control module? I'm going to find out myself here shortly but figured I'd ask before running out to AutoZone.

just get a set, its cheap :)

I started having problems again a few months ago, but I've also found a few places that repair our abs module. So if you haven't taken yours apart yet, then don't.

Yeah.. $12 bucks and an hour later I had the new to me module in.

The bottom left screw was a bitch.

So the $12 glue MOD works ? Today I went out to my 8 and heard a noise piped the hood and the pump was constantly running . Can you just remove the fuse and it be desirable?

Steering Angle Sensor
 

Hi,

Just wondering if anyone can help me.

I'm in Sydney, Australia and struggling to find a new steering angle sensor for my 2004 RX8.

Does anyone know where I could get one?

Thanks in advance!

Cheers

Harlan I am having a similar problem with my ABS. If I start the car hot (over 60F ambient) ABS doesn't work. Under 60, works great. Sounds like a continuity problem to me. Would you mind sharing the shops that can repair these units?

Symptoms
 

Great work on repairing your abs module. But aside from it not working I'm interested in if it was showing the same symptoms as mine before I tear into it. Mine runs continuously when power is applied. If that was the case with yours, too, then I am confident in choosing this repair path.