Code 21 - Now what?

[padgett]

Hokay, I put no trust in the Teves codes. Double M's case (lights out, felt ABS try to engage, pedal went to floor) matched a sticking main valve. I suspect the flush may have fixed it but if mine, I would want to examine/clean the passage to be sure.

The other 21 is different (ABS light comes on above 11 mph, brakes ok otherwise) . That one I do not think is the main valve and suspect a moving part. Suspect will neeed to look at the waveform from a spinning wheel.

The other possibility, a bad EBCM, has been swapped in one case.

Or it may turn out that someone has been inside the connector and gotten some wires shorted. Or the feed voltage is low.

Many things to check but some seem to just like to throw parts/money at it.

BTW how many realize the 90 EBCM is different from the 88-89 ?

[DAVES89]

Which connector? What lead do I check for low voltage?

My friend checked the main valve for both continuity as well as for voltage. I have the "approved" breakout box which he used at the EBCM and also checked at the main valve. He also looked at the main valve pigtail and as we decided one wire was discolored to install a different pigtail.

Also the reason I get/have parts is because I can buy them very cheap and much of this electrical stuff is over my head, but I still need to have any and every possible part at my buddy's disposal [i don't want to waste his time, and as he "moonlights" I can only get my car in for him to work on about every other week]. He is very skilled electronically [top grade ASE certified] and we go over the correct testing sequence together [with him explaining what he is doing and why] using the service manual.

Regarding throwing parts at it, not really, but why not have any and all parts? I bought my first Teves unit on Monday for $30.00 with a Riv switch that I sold to someone on this forum for $25.00 The second Teves unit I bought today for $75.00, but also got a working '90/91 IPC and three Headlight modules for Fieros and another Riv headlight switch with the Teves unit that will net me $155.00. Basically my Teves units are free, plus money to pay my friend for his time.

The only part my friend installed was the main valve, and he did it at my urging as he thought the ohm resistance was too close to being considered "bad." Like others on this forum, he has advised me to be sure that the EBCM is/was good. This I have done. [The Red now has the Black's working EBCM in it, ABS light still comes on and the Black has the Red's EBCM in it and the ABS light is off]. I am the one who swapped out the EBCM. I am the one that installed new front sensor leads [per your suggestion, which I agreed with, because the ABS light coming on at 11 mph is an indication of bad sensors] as the ones on the car were frayed. The light still comes on at 11 mph.

Our next step is to check the wheel sensors for millivolts [per McReattas suggestion] and if that checks out to then install the main valve that I got today with the lower ohm resistance.

I don't trust the codes either, but I am surprised that I have a different issue then Double M yet we both get the same code, very confusing to me. When I had this ABS light issue before with both the Red and the Black I would get two and one time three codes, but this time only one code, a code which does not indicate a wheel sensor issue at all.

My friend also tested the two existing main valves that I have [which are also sensors and read 4.9 and 5.1 which are close enough resistance wise for the manual to clearly state replace the main valve] and he determined that I should get one with a lower ohms resistance [which appears to be aprox. 4.2 ohm resistance, which my Black has and what Jim Finns car has] which I have done. BTW the "thump" in the pedal appears to be stronger with the 4.9 ohm valve then the 5.1 valve then what I had been experiencing [could be my imagination] but Double M [thinking from my memory, he doesn't get the "thump" at all].

Padgett I hope this post doesn't sound like I am lashing out, as I need yours and others advice to resolve this issue. My brakes work great, [no hard pedal or pedal going to the floor, just an ABS light] I just am confused as to why, what as always been a simple resolution [new sensor leads] has not cured my problem.

Edited August 12, 2011 by DAVES89 (see edit history)

[Guest Mc_Reatta]

Keep the faith Dave!

You (and others) are providing a vital service to the cause of furthering the advance of knowledge and understanding of our collective passion and poison, the Reatta.

We thought that we had a fairly good understanding of the Teves system and how to keep it performing by doing the brake test, and checking sensor wires and reading codes and changing accumulators, switches, motors, and relays.

While we knew that there were some issues with the Teves trouble codes, we now know they are even less helpful than we thought in other areas as well.

We had not given much thought to a main valve before you and DoubleM brought your problems to out attention, and now we know that this part can set a code and turn the yellow light on, is testable (although we may not currently know the acceptable limits), and that it is replaceable without replacing the entire hydraulic unit.

Time will tell how prevalent an issue these valves might be, as more or us with the yellow light on all the time start to undertake the testing of it along with the other usual suspects to try to figure out why this light stays on.

You are especially helpful to this effort because you have do have access to inexpensive replacement parts, and have the ability and motivation to implement the ideas and instructions that are thrown your way and respond with clear and concise information on what works and what doesn't.

Knowledge doesn't always come easily, and usually incurs costs of time, money, and frustration, but that's how we learn. It would be easier if those with the ideas, the test equipment and the problems were all in the same place at the same time, but we are usually hundreds or thousands of miles apart.

Keep up doing what you do well, and Ronnie will soon be able to add another test to his database (another vital link in the chain) that will further the lot of all of us on this forum.

It takes a village to keep a Reatta on the road, and this forum is (usually) a wonderful village!

[padgett]

On the EBCM connector, 1 is ground, 2 is fed from the 5a fuse when the key is on. 3 & 20 get power from the ABS relay which is energised by pin 8. So the key must be on for the ABS relay to energise. (or apply 12v to connector pin 8).

Page 5E1-22 of the FSM (available online) says that "Virtually any abnormal condition in the main valve crircuit coud cause ABS Code 21 to set." That page also lists seven conditions, only two of which relate to the Main Valve device, which will set a code 21.

None relate to a stuck shuttle, only electrical considerations.

The fact that it occurs when you cross 11 mph makes me wonder if there is a short in the cable since that is when things turn on.

Please I really appreciate the fact that someone has invested in the tools needed for someone else to troubleshoot. Part of the issue is that we are simultaneouly dealing with two different code 21s. Same code but completely different circumstances.

Add in that the FSM treats the EBCM as a "black box" (well it treats all of the modules as black boxes just some we know more about than others.) and it is difficult to diagnose particularly via remote control.

That said if you get the "thump", the Main Valve is working properly at POST and from the seven possible problems, I would eliminate"open solenoid" and "shorted solenoid" & concentrate on the other five.

[Ronnie]

Dave, I've been following your posts about the code 21 problem closely. I admire your tenacity in seeking a solution to fix the problem. We are all learning from your experience. I have worn my eyeballs out looking at the FSM but so far I don't have anything new to offer to help you.

I hope we can learn how to troubleshoot this code 21 one problem to the point where I could post instructions for doing it on ReattaOwner.com.

[Ronnie]

Dave, I just noticed that the FSM says the ECBM looks at the wheel sensors differently when the brake pedal is being pushed down. Just a shot in the dark but could you try holding the brake pedal down part way while accelerating up to and past the 11 mile per hour mark to see if the yellow light still comes on at the same speed?

[padgett]

OK. At this point there are two wires that go to the Main Valve. A short or open in either will set a code 21 if we believe the book.

From your description, the error occurs when you cross 11 mph.

What I would do now is instrument the two connections, ckt 856 (power) and ckt 150J (ground). Then first verify activation at end of POST (thump) and second look for a change in either at 11 mph.

An incredible amount of engineering is just boring repetition looking for differences.

[DAVES89]

Thanks for the support!

McReatta... not so much frustration, I did what I could, my buddy has pretty much taken over. Money? As stated before my parts are virtually free as the guys at this Pick n Pull like me and I sell parts to other to finance this obsession. Time? Truth be told all I did was walk out in the yard with my cell phone and picked out the car I wanted the Teves unit from, called the office, they sent out an end loader to bring in the car, then they pulled the part and sold it to me for $30.00.

I am just out research time and testing and installation of aforementioned items.

As my shop manual and parts are now over at my buddys house I will print off these latest posts [43,44,46,47 and any other ones you guys have ideas for doing] and take those over on Thursday.

As always thanks for your help. With the three of you, Padgett, McReatta and Ronnie, how can I fail?

I really think it is going to be a bad sensor or that main valve. If you remember this whole thing started with the Red light not coming on and then intermittant flashing of the ABS light on corners [right turns and going down grades] and going off on left turns and going up grades, or stopping the car and cycling the key..