ABS Control Module

[Kirky21]

Hello everyone! I just joined and have a question for anyone who can assist.
I have an OBS 2000 K2500 5.7L Vin R crew cab 4x4.
I am having trouble getting my OBDII to connect (there is power) and provide me with codes for a check engine light. I took it into the Chevy dealer and they have been going from module to module trying to diagnose why it won’t connect. They finally noted after 2 days that it is a bad EBCM (electronic brake control module) (abs control module same thing?) part# 12474923. They noted that when it was unplugged, boom everything started working again.

They noted that this part is discontinued and they cannot get it. My question is can I simply leave the abs module unplugged without issues occurring. When I asked them they said that it would cause problems as it is used as a circuit so if disabled it will cause issues. But with it unplugged they said the obd2 worked.

I just want to be able to read the trouble codes, fix those issues, and get my truck running great again.
Any help would be much appreciated

 

[df2x4]

I'm interested in what you find out/end up doing because I've been mentally preparing for this with my '97s. So far their ABS is still working OK, but I'd like a long term solution in case they decide not to. I believe the issue with just unplugging the ABS module is that if air gets trapped in it you'll have no way to bleed it out, I could be wrong though.

From what I understand you can replace the ABS module with either a junkyard '88-'94 proportioning valve and front lines, or an aftermarket adjustable combination/proportioning valve and possibly a residual valve for the rear drums with custom lines. I made a thread about it here but haven't gotten real deep into the research yet.

https://www.gmt400.com/threads/95-abs-removal-questions.53662/

IIRC there was a member here who opened up one of the later ABS modules and managed to fix it or at least diagnose what was wrong, but I can't seem to find the thread...

Are you primarily interested in resolving the electrical issue or eliminating the ABS entirely? If it's the latter, I can move this thread to the "Axles & Brakes" section so it might get some more attention.

 

[DonYukon]

My abs has been unplugged for 4 years no issues . Can’t have ABS with 1978 Dana 60 front axles lol obviously any lockup’s will be driver controlled but I haven’t had issues

 

[Kirky21]

Thank you DonYukon for the 4 years worth of experience with it unplugged and having no issues. I know the dealership can’t legally tell me to “just unplug it” but if the only issue with unplugging it is not having the abs active I am okay with that. I’ve seen a few videos with folks removing the fuse because the abs became dangerous by locking up the only some of the wheels or not allowing them to stop and almost crashing so they removed the fuse and have enjoyed it. But haven’t seen much of anything on the actual unplugging. So thank you again!

df2x4 thank you as well for your insight on this. My thinking is if I unplug it and it goes soft pedal on me eventually I could always plug it back in and bleed and unplug it again until next time. It wouldn’t bother me at all to make that a maintenance habit. Much like changing oil. Change the oil, change the oil filter. In this scenario, plug the abs module in to bleed the brakes, and unplug it again when done.

For the OBDII issue with powering on a scanner but not connecting, I could unplug and read the codes, fix those issues and plug it back in. Unless the abs control module is throwing something else off on my truck it sounds like it could work. I may get a few more codes related to abs because I unplugged it but I can ignore those and focus on the true engine codes thrown.

I did see a video online of someone taking apart their abs control module and shown where some soldering was cracked causing less connection and he resoldered those locations and worked like a charm but that was when I fell into the rabbit hole of videos and now I can’t find it but I believe it was the NBS 2000 silverado

what lead me to the dealership was I took my truck in to Firestone where I live in FL for issues with crank no start after the truck sat for a couple of days. Also rich exhaust and intermittent idling and shutting off. Once the truck was at temp though it was fine for the rest of the day. Check engine lights always been on since I’ve owned it so I took it up there to get it serviced. But they said without being able to read the codes we would just be throwing money at it until the problem was fixed. With 320k miles it could be anything in electrical to fuel to vacuum. That’s when I made the decision to take it to the dealer to try to navigate the wiring to find the problem. The dealer noted that in the obdII port one of the pins that was suppose to read 12v was only reading 2.5v so yes power turned scanner on but barely any power. So they started chasing wires and going from module to module as they didn’t think it was a pcm/ecm issue necessarily. When they unplugged the abs control module the obdII worked.

I called this afternoon and left a message to see if they could pull codes for me while it’s there but didn’t hear back by end of business day. Tomorrow I will find out if they could get codes pulled.

I may still buy a used abs control module and replace it to see if it works but that will be a week or so as I will be trying to get the immediate issues fixed based on codes provided. I will update with any progress.

if you think moving this thread to the axles and brakes section will help further please do so. Otherwise I will update on my progress with this truck.
Thanks again fellas!

 

[df2x4]

df2x4 thank you as well for your insight on this. My thinking is if I unplug it and it goes soft pedal on me eventually I could always plug it back in and bleed and unplug it again until next time.

You're welcome, but I see an issue with this approach. If you can't connect to the truck with a scanner while the ABS module is plugged in, you can't command the ABS to stay open during the bleeding process. You can't bleed the ABS module if you can't communicate with it.

 

[Kirky21]

Granted I don’t know how long the abs control module has been “bad” when I replaced the master cylinder, we bled each wheel and for the control module, there is a rubber cap on the drivers side of the module, if removed you can bleed that module similar to how you bleed the wheels. You press the brakes with the engine off and press the pin in and fluid squirts out and then let off the brakes and pin cannot be pressed and press brakes again to press pin, continuing this step until the brakes stiffen back up. Brakes have been great since and this was almost 1 1/2 years ago. I assume the same can be done again.

 

[df2x4]

Someone who knows more about these will probably chime in, but I don't think pressing that pin in produces the same results as bleeding the module with a Tech 2 or equivalent bi-directional scanner. You may be able to remove some air that way but I'm pretty sure bleeding with a scanner is the only way to be 100% sure you got all of it.