TrentC

So, I been having ABS issues for a long while, but the ABS light would only randomly come on maybe once every few months then go out. Added to that, a groaning sound come from under the hood when hard braking.

Now the ABS light is coming on a lot more often, and other small issues I am experiencing with the ABS system. With that, I was finally able to get the code from a flashing ABS light after jumping the pins under the dash.

Code 51 is referring to a valve relay malfunction. From some research, it seems to me the following similar device under the hood on driver's side (not my own), or a relay inside of it. Which would probably also explain the groaning sound I am hearing:




I am not seeing such a device being sold anywhere.

Is this a readily serviceable part, or must the whole thing be replaced? If it needs to be replaced, where can one be found? If it is serviceable. any suggestions on that?


Thanks a bunch!

oilcanhenry

https://www.ebay.com/itm/ABS-Control...YAAOSwQcZblU9T

TrentC

So in other words: NO

I see AutoZone sells a similar named device, but looks nothing like control module the image above. I guess I will have to stop by and take a look at it.

I am not even seeing anything online for sale resembling the control module in the image. I did find a drawing where the whole assembly is being described as a "
Thanks for taking the time to reply!

Sabino56

I had similar problem on my 93 with same abs unit. No one makes it and it’s not serviceable (or the market $ for someone trying to fill that niche isn’t worth the risk). You have two choices. Drive around with known bad abs and yellow light on or remove it and replumb brake lines between proportioning valve and lines going to wheels.

If you google the question you’ll see the typical internet spectrum of passionate opinions, debates on legality, what’s safest, etc. In the end, it’s a personal choice.

I have to believe that they designed the abs so that if any of the electrical solenoids & valves went bad the brakes will not fail. So as long as there aren’t leaks from the unit you’re probably ok driving it forever. I decided to remove it because something inside had shorted and toasted a wire + it just bugged me driving with known bad abs and the yellow light. I’d rather have known good non-abs brakes.

If you remove the abs you have to make your own lines. The nut sizes for inlets & outlets from abs are odd sizes for tube diameters so you can’t just make little “jumpers”. I ended up going from the proportioning valve and replicating the flexing coils in lines. It’s not too hard with the CuNi brake lines. In my case, removing the power feed to the system took away the yellow light. I’ve read that some had problems with yellow light remaining on. I guess the code in my ECU was designed for both abs and non-abs applications.

good luck!

TrentC

I did find this online about it.




Then from that I was able to find a reference to https://modulemaster.com which rebuilds/repairs, but that was 10 years ago, and seems they no longer do it for that module.

I am dealing with a annual safety inspection where there is an automatic fail for any engine lights on, though I am not sure about ABS.

I think I am going to try some junk yards. I see on car-part.com there are quite a few 1994 Suburbans in yards for parts picking.

I would rather get it repaired/rebuilt, though I may not have a choice.

Thanks for the input!

Sabino56

These units are evidentially not easy to bleed so I’d suggest reading up a bit before attempting to replace. It takes some special tool to hold open some valve when bleeding but seems doable. This article talks about it.

I’d be interested in knowing if you can find something reasonable at a salvage yard. When I removed mine I kept the unit and brake lines with idea I’d look into fixing or replacing eventually. My experience over the years is for anything no longer available in aftermarket they are aware and price accordingly.

don't know if a brake light would be counted as a CEL at emissions. You might see if removing power to unit turns off the light or no. Memory is power is thru a single wire to the power distribution block on firewall.

TrentC

Thanks for that information on the bleeding. I am not even sure were that tool could be had, and I am sure it is going to be expensive. I replaced the master cylinder a few months ago because the pedal could go all the way down to the floor. I took it to a cheap place to do all kinds of dirty work I did not want to do, so I had them also bleed the brakes also. After seeing the article you posted, I am thinking they did not do it correctly.

As far as the ABS light, I am dealing with safety inspection, not emissions. With that, I did find on the State's site which mentions this very issue, "NOTE: Anti-lock (ABS) lamp or signal which is on or comes on during test will not be cause for rejection." So I am good on that.

I will be traveling around for the next two weeks in a few days in the Suburban. During that time I plan on going to a few yards. Specifically the ones were I am seeing interior plastic in much better condition than. mine (and maybe a seat).

There are some very large yards in larger cities with just set the vehicles on blocks and let you pull anything you want off the vehicles yourself for much cheaper. They have names like Pick A Part, You Pull it, etc..

I will reply once I have one in hand, or some knowledge of pricing.

Thanks again!

Rednucleus

My 93 Sub ABS light has been on & no functioning ABS for many years. Brakes function normally like a non ABS system.

TrentC

Mine has issues though. Like when it first starts raining, the brakes will grab when barely touching the pedal. When braking hard, there is a loud groaning sound coming from under the hood, and then the brakes start acting unpredictable. Before I realized I needed to replace some vacuum hoses, it would actually cause the engine to stall. Sometimes they will lock up, or nearly not stop. Also lately, it seems pushing down on the pedal to make a stop is requiring more force than it should is needed.


Thanks for the input

Sabino56

I believe that abs bleeding procedure is only for replacing one to make sure the various accumulators or whatever don’t have any air in them. I’ve replaced master cylinder a few times and just bled brakes normally without problems when my abs was functioning. Some people recommend braking hard in gravel after bleeding to force the abs to cycle fluid thru it. I don’t know if that really does anything or not.

You could probably pull the fuse to the abs and confirm the groaning goes away and the brakes don’t grab, etc if you wanted to confirm its abs causing odd braking. It would set every code possible in abs so you’d need to reset it after.