If you have a 2020 GM truck and have braking systems error messages this article may help you understand why...

Service Trailer Brake System Message

This is from a post here from DriverDon. Thanks for information, Don.

Last week we called GM to try to get information on the integrated brake controller/EOH brake actuator compatibility issue. GM forwarded us to our local dealership's service department, which wasn't what we were after, but we did decide to make an appointment for them to look at the brake controller. Later that day I went into the dealership and said what I would really like is a list of the EOH brake actuators which GM successfully tested with, since their claim is that they are compatible with most EOH brake systems. This request was not met with great enthusiasm, but they did say they would contact GM to see if they had any suggestions to resolve our problem. Today they called to say that they were told we could use the Hydrastar HBA-CAM adapter with the Dexter actuator to solve this problem. After speaking with them, I was able to find this corroborating bulletin online: https://static.nhtsa.gov/odi/tsbs/20...73714-9999.pdf

One interesting thing in that bulletin is the statement that the GM integrated brake controller no longer differentiates between electromagnetic and EOH brake systems. Anyway, I still plan to do a test using a resistor network as an "adapter" later this week, I'll post my results here.