ABS Malfunction

[Guest SilverReatta]

I have a 1988 Reatta (two owners - my father and I). The ABS dash light is on nearly all the time, but intermittently. When the ABS light is off, the ABS system works fine; when it is off, the ABS is inoperable and the brake system operates in non-ABS mode (impossible to anticipate when a hard stop is needed!).

Recently, I brought my Reatta to a local dealership to fix a problem with the ABS system. They did the following work:

1. Replaced power master cylinder with remanufactured unit (from a company in Philadelphia)

2. Replaced valve block (GM part #1646523).

3. Tried swapping in another Body Control Module (BCM).

The yellow ABS dash light remains on intermittently. They also got a BCM code for "High Resistance", so perhaps this is a problem with the wiring. The dealership tried using a JTool pinout box to look for the source of the high resistance, but could not find it. Unfortunately, I paid over $1700 for the work and the dealership put in over 25 hours of work and we're at a standstill.

Someone suggested that I remove the ABS dashboard lightbulb (!), but it's not the light that's bothering me, it's the ABS problem.

I ran through the Reatta Brake Test (www.reatta.net/brakes/brakes_troubleshooting.html), with all results o.k. I didn't test the reservoir fluid switch, but would a faulty reservoir fluid switch cause the ABS system to malfunction?

Thank you for any ideas/assistance.

[Vincent Vega]

If you jump between h and b on the aldl, turn the ign to on, the ABS light will flash the code that set it. Ie.

blink blink, pause, blink blink blink= code 23. Code can be looked up in the FSM at Reatta.net. The FSM is for an 89. I think the codes will be the same.

[Guest EDBS0]

Wow Silver Reatta you have done almost everything except the wheel sensors.

There is also an Ate Controller for the Electronic Brake System in the trunk on the driver's side over the wheel well. My belief is that this controls the ABS not the BCM? Perhaps this is what they replaced?

Welcome and please feel free to share your location

[Jim]

This is a classic case of someone getting royally screwed at a GM dealership by an incompetent mechanic and a crooked shop foreman.

As Vincent Vega said, what they were supposed to do in the first place was read the ABS codes through the ALDL connector. The BCM and the master cylinder, 99% of the time, would not fix a yellow light being on. The valve body on the side of the unit could cause the problem but reading the codes first would have pointed to that unit. The problem is more than likely in the ABS computer in the trunk ( EBCM ), the sensors at the wheels or some connections in between.

I do have good EBCMs and wheel sensors if it turns out you have a faulty one. I can be reached at jfinn@cpinternet.com

[Edselguy]

I purchased my 89 a couple months ago, the yellow ABS light was on intermittently. I replaced the brake relay under the hood near the firewall and it has not come on since (except when I first start it).

[Guest SilverReatta]

The dealership says that they replaced (temporarily) the BCM from another Reatta but that it didn't fix the problem. They didn't say anything about the EBCM.

I'll check the ALDL codes and report back - very glad you all responded - thank you!

[Barney Eaton]

I am on the road (in Jim Finn country) so I don't have access to my reference material. but.........

Besides checking the codes, I would unplug and replug every connection under the hood associated with the brakes. I can't remember, but the fluid level sensor may also set the yellow light. try unplugging that(or it may need to be jumpered) I'm pretty sure the red BRAKE light will come on with low fluid or a bad sensor.

[Machiner 55]

Yes, you should check the ALDL output for codes and as mentioned, you should check the brake system relays. I currently have a condition where the amber anti-lock light as well as the red brake light come on intermittently due to the pressure switch/sensor on the TEVES pressure pump being bad. I know this because I swapped the switch/sensor from one car to another and the problem moved with the switch/sensor. Helps to have two (or more) identicle cars. If you are going to own a Reatta, it helps if you can do most of your own work. (unless you're independently wealthy) I guess you've just found this out the hard (read expensive) way. The relays are about $10-$12.00. Cheaper from "Shelby" on this forum. If you have the type of relays that can be opened up without breaking the case (some can, some can't because they are sealed) you could use a piece of crocus cloth to brighten up the contacts (provided of course the coil is functioning properly) then it costs you practicaly nothing. The pressure switch/sensor costs about $45.00 used and about $100.00 new. If you are going to do your own work the a Factory Service manual is a absolute must. Helm has them and you can find used ones on Ebay for between $50.00 and $100.00. There is an online version at www.reatta.net.

jfinn@cpinternet.com is an excellent source for good used parts.

Oh... yah, good idea to leave the annunciator bulb intact. It's there for a reason.

Good luck.

[Guest SilverReatta]

Again, good advice. I'll check the brake system relays as you suggested and unplugging/replugging in every connection that I can find/get to that is associated with the brake system. Fortunately, I have a Factory Service manual (interesting reading!) which has helped me quite a bit in the past (along with this forum).

At the very least, having gone through this, I'll be able help out on this forum topic.

[Guest MauiWowee]

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">

At the very least, having gone through this, I'll be able help out on this forum topic. </div></div>

Another member of this forum, F14Crazy, has become the the self dubbed "go-to-guy" on many topics for that exact reason. He's an asset. As he puts it "Every other part replaced/repaired."

[Guest tomt]

Back to the brake relay:

I had same problem, and that fixed it. Buick dealer had in stock. I'm thinking it must also have been used on some other models.

[Guest SilverReatta]

Replacing the brake relay helped (cleared an ALDL code). Still am getting an ALDL code for the front right wheel speed sensor (code 76). Turns out that the toothed sensor rings have some damage which may be causing this code (the wheel speed sensor output is fine). Could this code 76 also be caused by an EBCM problem?

[Guest MauiWowee]

Relative to this thread, I finally got around to reading my ABS code, and it is the lft frt sensor (#25). The manual refers to either the sensor or the wiring. Might it also be the ring, as above? Are sensors dealer only items? Guess I'll have to break out the old multimeter.

[Machiner 55]

[color:\\"red\\"] See Attached.

On pages 5E-14 and 5E-15 of the manual, the wheel speed sensors are discussed. Page 5E-14 has a diagram of the wheel speed sensor but, that is not what I want you to take note of. It's the close proximity of the lower control arm ball-joint nut to the toothed sensor ring. It's real easy for someone trying to remove the ball-joint to stick a wedge of some type between the toothed ring and the tapered stud of the ball-joint when trying to remove same. Damaging the teeth on the ring in the process. (I know... I did that very (stupid) thing myself not too long ago.) The manual, on page 5E-15 states that the clearance between the sensor and the teeth on the ring is to be set at .020". That's the thickness of five sheets of printer paper.

I suggest that before anyone gets crazy with meters and such or, suspecting computer problems (which may or may not be at fault) that they perform a visual inspection of the sensor ring tooth / speed sensor gap and use a feeler gauge. Especially if they started noticing errors after having front end work done on their cars.

If you find that the teeth have in fact been damaged, they can be repaired. All that's required is the removal, disassembly and thorough cleaning of the CV joint, filing away the mushroomed over portion of the teeth, running a bead of weld over the tooth (careful not to burn away what's remaining of the tooth or filling in the valleys) and then reshaping the tooth with a die grinder or Dremel then finish shaping with a file. (this is how I undid my stupid thing)

One more tidbit. Good luck attempting to remove the sensor from it's bracket. Even with the anti-corrosion coating that was to be put on during assembly, it's still seems that they are welded in place. I'm not saying that you need to remove them but be wary if you try. They need to be removed from their brackets only if they are being replaced, not for adjusting the .020" clearance.

Just my .02

[Guest F14CRAZY]

"If you don't have anything good to say, don't say anything"

Haven't had any experience with ABS trouble outside of the stuff convered in the brake test. I actually still need to do the ASDL trick to my coupe.

I'd help if I could

[manikmekanik]

I would question the competence of a GM dealer shop who, (after charging $1700 for a brake service which did not repair the problem), sent you home with a malfunctioning ABS system, placing you at risk.

Time for a call to GM customer service, for an investigation into the problem with your dealer's shop practices.

[lilredsreatta]

Just wanted to thank you guys I just start driving my Reatta and now my ABS light is on my is staying on. I am so glad for this forum, anything that goes wrong I come running here.

[Guest SilverReatta]

After getting it fixed properly and preparing the history, I was planning on writing to the dealership management, but as you suggest, GM customer service might be a better call (maybe both).

By the way, even worse, the dealership also sent it out with a leaking left rear brake line. Got the red light soon after I brought my Reatta home, refilled the brake fluid reservoir and within a day it had leaked enough to trip the red light again!

[Guest SilverReatta]

88_89_ReattaJohn, your $.02 is right on. Unfortunately, the teeth on the front toothed sensor ring are chewed up enough that I'm just going to replace it (drive axel). I'll let you all know if that fixes the problem.

I've found (and learned from this forum) that the ABS light on problem has a number of causes. Better to diagnose on your own before you bring it to the shop!

[Machiner 55]

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body"> Better to diagnose on your own before you bring it to the shop! </div></div>

Now you're tawk'n!

As with health care, people have to "take possession" of of their health care needs and not leave all the desisions up to the healthcare "professionals". The same hold true with car care. With shop rates between $50 and $75.00 an hour who but the wealthy can afford to have some technician spend hours guessing what's wrong whith your car. Even if you don't have the tools, equipment, skills, expertise or the time to do the work yourself, you can still arm yourself with the knowlege from the manuals and the folks on this forum so that you won't be taken for a ride (or a rube) when it comes time to turn the car over to the "professionals".

I've saved literaly thousands of dollars by using the information gleaned from the posts on this forum alone. Of course, since I'm a Wrench by trade (not automotive wrenching) I've got a fairly good selection of tools, and other assorted equipment along with a work space to work on my own cars. The only things I can't do are automatic transmission rebuilds, tire mounting and front end alignments. Oh... and painting.

Anyway... Glad to help. I've been helped so much by the folks on this forum that it's nice to be able to give back. My only problem is that I don't type or compose text very fast. It took me about two hours to put together the post regarding the cargo lock cylinder. Wears me out sometime. But if someone can benefit from it then it's all worthwhile.

I'm worn out now, bye.

[Guest tomt]

Right On John:

Unfortunately, I travel 80% in my job, and really can't do the work myself. I have found that if you find a good basic mechanic, and add what you get from the forum, you get the kind of mechanic that we'd all like to find. The trick is getting a good mechanic who will listen. With my TR-6, and now with the Reatta, I have been lucky enough to get the answers, and feed them to somebody who can do the work. My learning here, saves me the diagonstic work, which so often is wrong. Case in point, was my ABS light. The problem wasn't pointed out by my brake shop or Buick dealer. When I told him that the consensus was to replace the relay, he did it. Case closed.

[Guest SilverReatta]

Replaced the drive axle, which fixed the front toothed sensor ring and got rid of the code 76. Also found corroded terminals in the ABS main relay and ABS pump relay and replaced both of these. Now getting the 75 code (left front wheel speed sensor tests "open" so I need to replace it).

The dealer (another, not the crooked first one!) says that GM has discontinued these sensors and there is no stock available from GM. Does anyone know of a source for a left front wheel sensor?

Thanks!

[padgett]

I suspect that Jim Finn has some.

[manikmekanik]

In another post, Delores said she had recently recieved a new WSS which was bad, and was able to get it replaced.

Sounds like there are new ones available, ask Delores to post the outlet where she found them.

See "yellow light" post from Padgett.

[Guest Dolores]

Hi Guys,

Well, I'm still having the same problem with the left sensor. My mechanic has tested three left sensors from AC Delco ALL BAD. Even though they are within the required ohms, something about the magnetic pull. Anyhow, the warehouse (AC delco) has 40 in stock all with a similar manufacturing number we tried both varieties and still no luck. So we have to assume all are bad - at least that's what my mechanic said. He found the same left sensor that is used for a Jaguar. Double the cost but if it fixes the problem it's worth it. He is to get the part today so I'll let you know if the fat lady sings today If she does sing, my mechanic will write a post for the forum to explain it in mechanical terminology. If not, we are back to square one.

[manikmekanik]

If the Jaguar sensor test-out as good, as the others have, then I would go back to examining the car for another problem causing "tested-good" sensors to not function properly.

Check all wiring to the sensor, and check-out the EBCM circuit, wiring, and connector.

[Guest Dolores]

Guess what! The FAT LADY SANG! The jaguar sensor turned out to be too short but we were able to secure a used reatta left sensor from another source. And it had the magnetic pull my mechanic was looking for. I'm so happy the yellow light is out, I still can't believe it! After almost a year when the initial light went on, it finally is history hopefully never to return. My mechanic said he would write something up for me to post on the brake issue. Once again, I'm a happy Reatta owner but how far will I go? See my next post.

[Guest SilverReatta]

Congratulations, Dolores; I know how annoying that persistent yellow light can be...

My mechanic says that he contacted AC Delco and they didn't have any in stock, so the used route looks like the way to go. I still need a left front wheel speed sensor...does anyone know of a good source for this (used or new)?

[Guest MauiWowee]

I suggest a member of this board, Jim Finn, who has boatloads of such parts and is quick and fair. jfinn@cpinternet.com

[Guest SilverReatta]

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">I suggest a member of this board, Jim Finn, who has boatloads of such parts and is quick and fair. jfinn@cpinternet.com </div></div>

Thank you...Padgett had also suggested Jim, but for some reason, my first e-mail likely didn't get delivered to Jim. I've tried again...I know he's helped a number of folks on this forum.