Here is my recent struggle and victory over the EBCM failure my car had. Hope it might help someone else.

2008 Base C6 convertible, manual transmission. 2nd owner, purchased from Father in Law (FIL) so full life history and maintenance is known.



"Service Vehicle Soon" message appeared. Intermittent ABS and Brake light on dash. Sometimes with message “Service Active Handling System”. A couple times it would activate Traction Control and 1 or more brake calipers causing drive and control issues. I am convinced that an earlier minor incident where my FIL briefly lost control after over correcting on an unexpected traction a few years back was due to this same issues.



I fought this over a few months. Intermittent and random. San Diego car, garage kept. Didn’t matter if cold/hot. Sometimes no error lights or messages, then they would pop up after 20 minute drive.

I purchased an Innova 6100p scan tool for OBDII that can read the ABS codes.

Codes C0450-00 = Steering Assist Control Actuator Circuit

C0281-00 = Dynamic Rear Proportioning

C0550-00 = Electronic Control Unit

Also occasional wheel speed sensor codes: C0035-0F, C0040-0FC0045-0F, C0050-0F. Often all at the same time so this also pointed me to the EBCM.

EBCM unit looks to be the same from 2005-2009, perhaps 2010. It is an aluminum rectangular box at driver’s side front of engine. 4 small bolts at the corners hold it to the ABS manifold and pump (T25 torx). One big plug connector on the Driver’s side face connects to it. It releases with depressing a black plastic tab on the face and rotating the gray cam bar towards the rear of the car to cam release from the plug socket. Everything is very tight and it makes this difficult. Removing of the Driver’s front wheel can help with access to the bottom rearward bolt. A real bugger.

I ran through many of the checks from the service manual and many I found researching on this Forum. The VES steering rack system was all within specifications on resistance and not shorted. The wire harness from EBCM plug to steering rack plug was good.

I cleaned 3 main ground lug locations in the engine bay, including 2 accessed under the battery tray.

I cleaned all spade terminals and checked fuses and wire harnesses to fuse block. The Battery is less than three years old.

I removed the EBCM and checked all of the solder joints that I could see. Cleaned off the conformal coating and re-soldered ~10 of the main joints I could see, just in case there was a cold solder joint crack. This is a common theme in the C5 EBCMs and there are 5 solder pins that usually fix those units from what I have seen on forums and online videos.

The fix for me was to purchase a Salvaged EBCM (came with ABS pump and valve Manifold) and I swapped it in and it solved all errors and issues. (Driven daily for 1 week as of this post)



The Salvaged unit was from the same year and similar base model Vin. The label on the end had matching GM ASM PN 25847889 and GM ECU PN 25847891. I was concerned that I would need to program it with my VIN # with a better scan tool or at the dealer. I read here that a guy was able to swap one in and it worked without the reprogramming. This was my experience also.

VES power steering is back to full function with lower steering effort in slow turns like parking lots.

So this fixed mine. I have heard of others with a steering position sensor causing some similar errors and ABS issues.

I was tempted to send my EBCM to a repair service. Many can be found on ebay offering to fix these and others. A few are mentioned in various forum posts also.

The open face of the EBCM when removed from the ABS manifold, has the main printed circuit board and ABS valve coil actuators visible. There is a second printed circuit board underneath the top one. 3 small fasteners make it seem like you could remove the top board but it is a permanent install.

I went to bandsaw dissection to try to determine how possible fixing one of these could be. I have yet to identify the true cause of the problem. If it was a component on the bottom board, there is very little chance of servicing it in my opinion.

See pictures below. I hope this helps others out there.





ABS pump, valve block manifold and Electronic Brake Control Module (EBCM)





EBCM, 3 screws removed from top Circuit board.





Bandsaw cuts to remove case.





View from side with case flange cut away. Two Circuit boards soldered together. 30+ solder pins, 5 main all the way through to connector.





Top circuit board cut away from bottom board.





two screws mounting lower circuit board.





Bottom side of top circuit board. No blatant components with visible issues...





Lower circuit board pried off of glued pads at base, after Connector cut through on bandsaw.

 

Check your passenger drain udder. Mine was plugged and letting water drip directly into the EBCM when it rained. in my manual GS, I could grab it from under the hood with no issues since I have no battery in that location. You may need to disconnect the battery and get to it.

 

The computer over there is the ECM (engine control module). The EBCM (electronic brake control module) is in front of the engine on the driver side.

 

oof. you're right. I was thinking of BCM, not the brake controller.

the ECM is slightly shifted away from the BCM and the BCM gets leaked on.

 

Hack saw not needed, and as you pointed out, just need to de-solder the soldered pins that are holding the upper to lower board, if your looking for a cold solder joint problem.

Hence working something, and then having problems next is either cold solder joint problem (not component gone bad, or in many of the cases, not even a problem that you have to pull the ECBM, but just pull the connector to use spray electrical contact cleaner on that connector and the EBCM pins, since a problem there.

Really, short of a solenoid valve that is sticking or bound up, and can not MK flush the valves to clean up the corrosion in it/them (its cover peened into pump body housing, and not clean way to pull any of them to detail clean by hand) from not changing the brake fluid every few years to allow the water soaked brake fluid to cause corrosion problems in the vavles (brake fluid will pull moisture from the air, and how water gets in it), non of our codes where point to a problem with the valves.

So yes, there is the "throwing the baby out with the bath water approach", by replacing the EBCM with another unit, but did you try to just clean the connector and pins to the EBCM before you replace the unit?

 

Good job!
I think that the electronics are going to be the death of many of our cars as they grow older, especially since GM has quit manufacturing replacement parts, and the aftermarket suppliers won't make them because of the low volume requests. Newer cars are even worse.
These intemittant problems are the worst.