EBCM replacement, how to.

OK, since it was tough finding all this info in one spot I started a new thread with a How To guide.  I hope this helps.

First, I apoligize for not taking the photos of the EBCM while it was off the AV, but I got sidetracked trying to sell my IROC and when I got back to this I forgot about taking photos, but I still think this will be worth the reading time.  The close up photos for the EBCM is the only one I really missed so I took a photo of a photo I printed off the web.

For starters, here are photos of where things are located.  The ground that may need to be cleaned is located on the frame perch just under the drivers door.  The EBCM is mounted on the inside of the frame rail, pretty much under the drivers seat.  The 3 bolts that hold the pump/modulator and the EBCM to the frame rail are located thru these 3 holes.  Use a 6 point deep well socket, 13mm, with a 3" extension to help prevent dropping the bolts into the frame.  I suspect it will be very difficult, close to impossible, to reclaim them from inside the frame rail, SO DON'T DROP THEM.    The frame is notched to allow loosening the bolts and sliding the assembly forward where you can pull the bolt heads through the inside of the frame, but the brake lines are there and moving it forward would be a bunch more work. 

The first photo is from the drivers side, the second is a look from the passenger side.

If you want to try cleaning the ground it is probably the simplist step in chasing this problem.  Just back out the screw, use some sand paper or a wire brush and chean up the frame survace around the hole and the 2 eyelets for the ground wires.  Mine looked good on the outside and when I pulled it off the frame.....it still looked pretty good.  I cleaned them anyways, but it didn't fix my problem.    It is worth the 5 minute effort.

Inside the frame rail you will find the antilock pump, modulator and the EBCM that is mounted on top of the modulator.  There are 4 small screws that hold the EBCM to the modulator and they use a T-15 T-20 torx bit for removal.  I used a bit that was about 2" long and with the assistance of a 1/4" socket on a 1/4" drive ratchet it was not too difficult to reach the screws, but you can't see them very good from below so you have to feel around a bit to find them.   

Edit:  Thanks to some info from TexasTom on related thread I found my problem was probably the wrong sized Torx bit.  Just because the T-15 fit doesn't mean it was the right size.  Please use a T-20 Torx bit.  I ran out and checked, it is a T-20.  Thanks goes to TexasTom.

This is the important part......before I started I used a hose to spray this area real good to clean off any loose dirt, but you will probably still need to use an ice pick or something similar to make sure all the dirt is out of the head of the screws.  I did not do that, because I did not know what would happen next.     3 of the screws loosened easily, but the head of the 4th screw stripped because the bit did not get in far enough.             If you strip out the screws, or you have another problem you will need to drop the entire unit from the frame rail.      The location of 2 of the screws is marked in the photo, the other two are in the same location near the top of the frame rail.

There are 2 electrical plugs that are easy to see in this first photo, the third plug goes to the pump and is on the back side, you will pretty much need to seperate the EBCM from the modulator to be able to reach it.  The second photo shows the 5 brake line fittings that need to be taken apart ONLY IF YOU HAVE TO DROP THE modulator.  You will need a 9/16" wrench, and although a line wrench is best you will need an open end wrench to loosen at least 2 of them.  The good thing is they were not as tight as I suspected so they came apart without much swearing trouble.

Almost forgot, the lines I have marked as 3 and 5 will need to be accessed by reaching over the top of the frame and applying the open end wrench from the top.  Have fun.   

If you have to break open the brake lines you will get a bunch of break fluid raining down on you.  Watch your eyes and have plenty of rags available.  I used 2 rags (about the size of an old pair of boxer briefs  ) and they did good at soaking up the fluid.  But remember, unless you want a new paint job to go with the new ebcm do not get the brake fluid on your paint, or any pretty surfaces.  Brake fluid will eat paint.

If you remove the ebcm you will need to keep the mounting surface clean.  There are claims you can drive without the ebcm module but the installation instructions I got back from ModuleMaster.com said to clean the modulator with Brake Clean and then heat is with a hair dryer to make sure it is dry before remounting the ebcm.  If you left this on the AV and drive it around it will be very difficult to see if you actually have it clean before you put things back together.

This is what the EBCM looks like.  the part with the 6 holes is what mounts on the 6 posts from the modulator.  You can see the 4 screw holes for the mounting screws.  The 2 plugs together are the ones you can see from underneath the AV, the 3 plug by itself is for the plug to the ABS motor.

Once it is installed, plug in the last 2 plugs that are accessible from the below the AV.  If you had to pull the modulator don't bother trying to bleed any of these 5 fittings.  It isn't worth the effort.  Quite frankly there simply is not enough room to turn the fitting so just tighten them up and head for the wheel cylinders.  Because I had new fluid in the master cylinder I was able to, with the help of a friend (thanks Denman), bleed each cylinder until the bubbles stopped and the new clear fluid was coming from each bleeder valve.  Remember to do this with the engine off.  After one wheel there was not much difference in the brake pedal.  The pedal started getting firmer after the second wheel.  By the third wheel the pedal was feeling pretty good and after the forth wheel was completed the brake pedal was back to normal. 

Remember to test the brake pedal while in park with the engine running and make sure it feels good before you shift into any gear!  Testing the brake pedal while the AV is moving is not a good time to find out the brakes are not holding. 

Hope this helps.

6 days and all is well.  My brakes work  and the trouble lights quit coming on.  Best part is my battery is no longer dying when parked overnight.  I am convinced the EBCM was causing the battery drain.  (I hope  ) 

Side note,  I am still getting the (restraint) U1041 trouble code.    Not sure what that is, but the other code, (HUD) U1041, is gone.  I am taking it to my friends automotive shop Monday for a transmission fluid/filter change ( I know but I don't have time to mess with it) and I will check with him to see if he knows what the cause might be.  I suspect it could be one of the other ABS parts acting goofy, I hope nothing serious.  I will let you know, but so far so good.

     

No one else has replied to my How Too instructions.         

THANK YOu!!  I just checked the forum tonight because I'm getting the idiot lights and the dealer said it was $1300 to fix the EBCM "short".  I said no.

He did tell me that if I heard a noise after I turn the truck off, the EBCM with a short can cause the pump to run and run, .... running down the battery..... and if this started to happen, to just pull the breaker on the ACS system with no ill effect EXCEPT no ABS, which I wouldn't have with the lights lit anyway.

I was thinking of doing this project myself...  A private brake shop said they'd do it for $750.  So, now with your instructions.... I might try to do it myself.  I am going to check that ground first though...

Thanks again for the posts!

Updated info for post #3.  The proper size Torx bit is T-20.

INresponse said:

Inside the frame rail you will find the antilock pump, modulator and the EBCM that is mounted on top of the modulator.  There are 4 small screws that hold the EBCM to the modulator and they use a T-15 T-20 torx bit for removal.  I used a bit that was about 2" long and with the assistance of a 1/4" socket on a 1/4" drive ratchet it was not too difficult to reach the screws, but you can't see them very good from below so you have to feel around a bit to find them.   

Edit:   Thanks to some info from TexasTom on related thread I found my problem was probably the wrong sized Torx bit.  Just because the T-15 fit doesn't mean it was the right size.  Please use a T-20 Torx bit.  I ran out and checked, it is a T-20.  Thanks goes to TexasTom.

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Please remember to use the T-20 torx bit on the factory screws holding the EBCM to the modulator.  My original write up, and the reason I ended up with the big headache, was wrong.  The screws use a T-20, not a T-15.

I'm chasing down the common mushy break pedal issue on my 02, but wanted to share the love on your post!

Thanks for the kind words.  I never had an issue with a mushy brake peddal, but I suppose it would be easy to have an air bubble in there.

Good luck with that.

INresponse said:

Thanks for the kind words.  I never had an issue with a mushy brake peddal, but I suppose it would be easy to have an air bubble in there.

Good luck with that.

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I would have responded but I happened to be on the scene that day and saw it all live...Job well done and an excellent reference article to boot!!

I had mine replaced last week under the extended warrenty. No cost to me, but the warrenty people paid out 997.00

Denman said:

I would have responded but I happened to be on the scene that day and saw it all live...Job well done and an excellent reference article to boot!!

Click to expand...

  Thanks again for the help. 

MEDICO said:

I had mine replaced last week under the extended warrenty. No cost to me, but the warrenty people paid out 997.00

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Don't take it personal but  , take that for cheating.  You missed out on all the fun. 

That was nice of you to do that. 

I'm reading up on brakes because mine act a bit funny. If I brake light  or hard, everything is fine; but if i hit it medium, then it pulses. It's not hard like ABS oscillations, but I can feel a slight up down motion. I only have 59K miles on my 02 and the pads are less than a year old all around.

Just saw this on an old post, probably my problem:

I had the same problem with my 02 Z71.  My brakes would pulsate pretty bad when braking.   I had my front rotors replaced a few weeks ago and the pulsating faded but came back in a few days.  I also had bad rotors on the rear that needed to be repaced.  So yesterday I did the complete brake job.  Shocked  Replaced my rear rotors and replaced all the pad with new one.  I even took the extra step to bleed the entire system just for good measure.  Now my brakes feel so good!!! Cheesy  It still has the soft feel in the pedal like normal from the factory, but I can feel the difference in the system.  It feels almost like a new truck again.  I don't know why I didn't do this earlier.  So for the pulsating brakes, try to replace the rotors if they are worn, then the pads, and bleed the system.  It worked for me.

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I see you have a pic showing brake lines 1 thru 5 going to the EBCM. Could you PLEASE tell me where the other ends of these lines go? I replaced all of the lines and EBCM, and want to be sure the lines are in correctly. The Chevy Service dept. can't help. I'm lost. Can you help?

    Thank you,
    Contender
    tjmullen@yahoo.com

Contender said:

I see you have a pic showing brake lines 1 thru 5 going to the EBCM. Could you PLEASE tell me where the other ends of these lines go? I replaced all of the lines and EBCM, and want to be sure the lines are in correctly. The Chevy Service dept. can't help. I'm lost. Can you help?

     Thank you,
     Contender
     tjmullen@yahoo.com

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I don't know where they go, and I don't think I am qualified to guess and hope you and your family will be safe with the outcome.  I think you need to find another AV close by and sketch yourself a diagram.

Good luck, and sorry.

edit to clarify:  I don't know what year or model AV you have.  I don't know if they changed by year, or if they did something different from 2 wheel drive to 4 wheel drive.  Also, my AV is not home right now but I recall that the brake lines get lost behind other things and a guess on my part may end up with life threatening results.  If you have the lines you took off they should be bent in a way that you can hold them up underneath and get a good idea where each line goes.

I have a 2002 Z71, 4WD, 5.3. My main concern is to find out where the front and rear Master cylinder lines go. They may be the easier ones to follow. If anyone can help it would be greatly appreciated. The old lines were so corroded they fell apart.

  Thanks much,
  Contender
  tjmullen@yahoo.com

On my 2002 Z71 4x4 1500 AV, in the photo I posted in the first post, lines 2 and 4 come from the master cylinder, lines 1 and 3 go to the front brakes, and line #5 goes to the rear breaks.

It looks like #3 goes to the right (passenger) front wrapping all the way around the front near the bottom of the radiator.

It looks like #4 goes to the front fitting on the master cylinder.

Hope this helps. 

Thank you ever so much!! All the lines match what you say. I bought a used EBCM, couldn't bleed the brakes. Thought I might have installed the new lines incorrectly. Must be a bad EBCM.
  I truly love my AV but can't believe how bad the undercarriage looks. Brake lines, Drive shafts, Frame look like they were under water for years!

  Thank you so much again,
  Contender
  tjmullen@yahoo.com

Where do you live?  Somewhere near salt water or winter road salt?  Aside for some dust or dirt the underside of mine is very clean and rust free.  Most of the dirt is from playing on dirt roads in the desert, some from driving near construction sites around town.

Irwin, Pa (near Pittsburgh). But honestly, no one can believe how bad the underside looks. The driveshaft looks like a WW2 relic. My friend has a 1990 F-150 and his underside looks fine. here's something that may be a problem. I only put about 2500 miles on it last year. It did sit outdoors (on concrete driveway, not grass). If sitting caused the corrosion, then "Spread the word" of this potential problem.

Parked on concrete is not an issue.  Parking on grass could be depending on issues.  Did you buy this used?  I would suspect something got under there and coated the underside to promote the rust and, once started the problem continues.  Coulda ran through a puddle of something, could be salt that started it, who knows, but something initiated the rust.

Bought it new. Was one of the first people in our area to have one. Showed quite a few people how to "convert" it.
Excluding the underside, the body looks great (except for faded cladding).