Greetings. It's somewhat possible that you installed the wiring harness to the module incorrectly. It's a somewhat tricky (the first time) locking coupler that MUST be correctly and solidly seated before its lock can be safely secured. The lever MUST be in a position that allows ALL FOUR locking tabs to be FULLY ACCEPTED before the harness can be pushed all the way down. Only then can the lever be correctly engaged to push the connection "home" and locked. Failure to follow the proper locking procedure can possibly damage the locking mechanism (usually by breaking the plastic lock tabs) if it is incorrectly engaged.
It is my understanding that if the connection isn't locked right or if the lock is broken that it could cause the module to work improperly. When properly locked, the connection should be solid and not move AT ALL when wiggled.

I have seen it related that this has been the culprit on more than a few ABS modules after re-installation (even some done by independent shops) and this would be the first thing I'd check, beyond that, I've no other suggestions at the moment.