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abs ecm malfunction


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I have a 2004 GMC 2500HD SLE. In the past year, I have had the ABS/BRAKE alarm light go on intermittently.

I bought a scan tool to see what was going on. The code given is: C0550.

ECM malfunction.

Has anyone had a similar problem.

I am going to take it off and check the connections to be sure its not just a compromised connection or water in the connector, you know, something like that.

Those puppies are expensive.


Brakes work fine.


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its a pretty cut and dries diagnoses ,,,,,


DTC C0550
Circuit Description

The EBCM performs several self-tests for any internal problems which may affect proper operation.

Conditions for Running the DTC
  • The ignition is ON.
  • The engine is running at a rate greater than 450 RPM.
Conditions for Setting the DTC

The EBCM detects an internal malfunction.

Action Taken When the DTC Sets

The following actions may occur.

  • The EBCM disables the ABS/DRP.
  • The ABS indicator turns ON.
  • The brake warning indicator turns ON.
Conditions for Clearing the DTC

Certain failures that may cause this DTC to set cannot be cleared. Other failures that may cause this DTC to set may be cleared, at least temporarily, by using the scan tool Clear DTCs function.

Diagnostic Aids

Replace the EBCM if this DTC continues to set intermittently.

DTC C0550






Did you perform the ABS Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - ABS


Use a scan tool in order to clear the DTCs.

Can the DTC be cleared?

Go to Step 3

Go to Step 4


Start the engine and allow the engine to idle.

Does the DTC reset?

Go to Step 4

Go to Diagnostic Aids


Important: Following EBCM replacement, use the scan tool to perform the Tire Size Calibration procedure.

Replace the EBCM. Refer to Electronic Brake Control Module Replacement.

Did you complete the replacement?

Go to Step 5


  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

Go to Step 3

System OK

© 2014 General Motors. All rights reserved.


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  • 2 years later...

As long as you have good power and ground circuits to the ABS module it's going to indicate an internal problem in the module itself and it will need to be repaired or replaced

Are ABS codes the same as Engine codes. Repair the lowest number code first??

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IIRC, that was the code that showed up on my truck, along with the abs/brake light coming on. It wouldn't happen all the time, just every now and then, along with a 'service abs' message on the DIC.


What fixed it for me was cleaning the ground connection for the ABS computer. It's on the "wing" off the outside of the frame, just below the drivers door. Unbolted the two connectors, cleaned them as well as the surface of the wing, put on a smidgeon of dielectric grease and bolted them back down. Hasn't reoccurred for me in more than a year.

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