Hi,

I have a 1989 W250 and my Anti-Lock and Brake error lights are on. I would like to find out how to get the Anti-Lock light to flash for the codes. I am sure this is something that has already been covered and a link would be great, but I am posting this and cannot seem to find a cut and dry method to doing this. I have seen some stuff about grounding a connector pin or something but no pictures or anything. I am just looking for a detailed straight-forward procedure. Pics or video if its out there would be great. I want this system to work in the truck, despite so many people saying to bypass it. I will gladly sink the money into it to get it to work. Anyways, sorry if this is repetition from another post, I just need some guidance here. Thanks guys!

Usually when the light comes on it's because the RWAL freezes up, just replace it with a new one if you think you really need it. In case you don't know where it's located it's above the rear axle on the frame.

I was planning on replacing that anyways...good to know and thank you! I am still just trying to figure out how to get the Anti-Lock light to flash the codes...

I really don't think your going to get any codes. It's nothing like the newer ABS systems it's only a RWAL valve, no wheel sensors or anything else.

That's why most will just delete the RWAL valve and unplug the black box.

Well there is a wheel speed sensor on the top of the differential housing that uses a magnet on the ring gear or something near that to pickup wheel speed. Its not out of the transmission. There is a way to pull codes though. I understand its way before OBD-II but there is a factory scan tool called a DRB-II scanner that has the connector for it but it is a big money tool. There are things online and on youtube showing the codes and stuff but they either do not explain it well or show in the video how they have connected to the module to get the light to flash. But what I can tell you is that they aren't using any scan tool and they are grouding and powering certain pins on the module but I am not sure which...

There is only the RWAL valve in the system, and the magnetic pick up and ring gear on the axle to tell the ABS module what the axle is doing, not a lot of things you need a code(s) for. The fact no one has come forth with the information you are looking for, nor have you been able to find the DIY procedures anywhere on line think it shows you how little people care about this system being functional.

They were problematic when new, and never got better with age, hence the reason nearly 99% of people either disconnect the ABS module or bypass the RWAL valve. I did both and would not consider going back.

I like to make old stuff like that work. It is there, so I think it should work. Back then it was such an innovative new feature and I am the type to think that is really cool. That is my motivation to make it work, no matter how crazy that sounds. I will link a video here to show what I am talking about with the pin powering/grouding. It is a thing, it is just not specific enough as to how to do it. I am happy there is so little to go on with only 3 main components: the module, valve, and speed sensor. Here is the video link:

Have you tried posting on one of the other 1st Gen Dodge Forums, even the gas model trucks i'm sure have the RWAL's.

I just did a quick GOOGLE search and found this https://www.turbodieselregister.com/...are-on.113889/ There are alot more pages of info.

That was a lot of great info on that link. Pretty much exactly what I needed. Thank you so much!!

Since you was so set on fixing something you didn't need to I figured i'd help you find some info.

haha I appreciate that! I am sure i am of the 1% who wants to make it work, but that is why I want to make it work...thanks for your help and consistent responses, though even considering you disagree with me on fixing it lol

It's like I tell everyone that's dead set on something " it's your truck you can do what you want with it ". Even though we know of better ways of fixing things then Dodge did from the factory we can still help fix them to factory. This issue is just one of many on these old 1st Gens.