Sorry, but are you saying that even if I keep the current EBCM but swap the ABS hydraulic control unit (HCU, aka Hydraulic Modulator, Valve Block, or Pump Assembly) with one that works I still need to get ECBM reprogrammed?

Current EBCM with replacement HCU no then you don’t reprogram the EBCM .


These guys are recommended

https://repairlaboratory.com/repair-...torrent-1-900/

 

Why would you need to replace only the hydraulic part? Curiosity is killing me.

 

valve is stuck open, nothing is wrong with the EBCM portion

 

Then you just need to replace the hcu and bleed the system. Easy peasy!

 

I have never heard of that. What is the diagnostic, what are the symptoms?

 

I have a soft pedal that slowly moves to the floor of the car. This problem did not start after any brake work. The pedal is hard when the car is not running. Chat GPT Please list the possible causes of the soft pedal.That’s an excellent, detailed observation — and you’ve already ruled out an important clue: the brake pedal is firm with the engine off, but soft and slowly sinking when running.
That distinction helps narrow the problem significantly.

Here’s a structured list of the most likely causes, from most to least common, along with how to tell them apart:

🔧 1. Internal Leak in the Master Cylinder

Most common cause of a slow-sinking pedal with no visible leaks.

• What happens: The internal seals (cups) in the master cylinder bypass fluid internally when vacuum assist is applied.
  
• Why it’s soft only with engine running: The power booster amplifies pedal force, exposing a weak master cylinder seal.
  
• Test: With engine off, pump pedal to make it firm. Hold steady pressure and start the engine — if pedal sinks noticeably, the master cylinder is suspect.
  

⚙️ 2. Internal Bypass in ABS Hydraulic Control Unit (HCU)

• A stuck-open isolation or dump valve can cause internal leakage within the ABS block.
  
• Symptoms: Pedal firm when engine off, but sinks slowly when running; no fluid loss; sometimes worsens after ABS activation.
  
• Test: If system is well-bled and master cylinder is new or known good, and the pedal still sinks, suspect the HCU.
  
• Fix: Replace or professionally rebuild the ABS modulator.
  

💨 3. Air Trapped in Hydraulic Circuits (especially ABS unit)

• Even a small bubble inside the HCU or lines can compress, causing pedal softness.
  
• But: This usually causes a “spongy” feel, not a slow steady sink.
  
• Check: If brake work wasn’t done recently, trapped air is less likely unless fluid has boiled (from overheating).
  

🧱 4. Faulty Power Brake Booster (Vacuum Assist)

• A defective booster can occasionally cause pedal travel anomalies, though typically it makes the pedal hard, not soft.
  
• Rarely, a torn internal diaphragm can create inconsistent assist and make the pedal drop erratically.
  
• Test: With engine off, pump pedal several times to release vacuum, then start engine — if pedal sinks slightly (normal), that’s fine. If it dives rapidly, suspect booster or master.
  

🔩 5. Loose or Leaking Brake Line or Caliper

• External leaks always cause fluid loss and usually a spongy feel that worsens quickly.
  
• You said no brake work was done, so check for any dampness near calipers, hoses, or fittings anyway — a slow seep can mimic internal bypass symptoms over time.
  

🧪 6. Brake Fluid Contamination or Breakdown

• Old or contaminated fluid can damage seals in the master cylinder and ABS block.
  
• Look for: Dark, murky, or oily fluid.
  
• Contaminated fluid can cause internal seal swelling and slow bypassing even without external leaks.
  
  
  At this point I've changed the master cylinder, rear brakes (including cylinder), front brakes, including caliper and hoses. I've bled the brakes including an ABS scan tool bleed. Not much logically left except for a defective ABS. There is no fluid obstruction in any of the brake lines. Although the ABS dash light is not on, I have seen some you tube videos where it is not on even though a valve is stuck open. A stuck open valve can cause a soft pedal.
  

 

The test for a power brake booster is to pump the pedal up then turn the engine on with your foot still on the pedal; it should slowly go down.
I think you rely on ChatGPT and youtube too much. I have found ChatGPT to be radically wrong several times, it often uses facebook and other click bait sources for reference and youtube tries almost as hard as facebook to kill you. Many grains of salt are required.
I cite the many mentions that the rear brakes are all the same 2006-2011 which is completely wrong and the nearly universal thought that the suspension parts for LS/LT are identical to SS ( even GM parts is guilty).

 

Hi superdow. Did you ever figure out how to get that ABS module connector off? Was it just the clips on the side that need to be pressed in or something different? I am in a similar boat where I believe my ABS module is defective and I need to get it repaired by sending it in or buying a new one and having it programmed. How did things turn out for you?

 

I still don’t understand if you’re barking up the right tree, you posted earlier that you have C0050 and C0040, along with C0550 code

check out this information

https://www.coloradofans.com/threads/code-c0550.415112/

 

Thanks Oldblue! I really don't know and just trying to rule things out. I'm going to unplug the ABS module and take a look at the connector just to see if anything looks dirty or messed up. The last several trips I've only seen the C0550 code which never goes away. A little over a week ago I had all 4 wheel sensors show codes, and then a few days before that the same thing with all 4 sensors coding. A couple of weeks ago, only two of the wheel sensors were coding. Right now, I can drive around and see valid wheel sensor values with no wheel sensor codes, but the C0550 code won't go away, even if just for a second. I can see a lot of valid ABS live data.