Twingo c06 ABS+Handbrake light lights up

Hello, I have the following problem. With me the ABS + handbrake light has been shining permanently for a long time. I have already pulled out all the plugs, cleaned and provided with contact spray. It has already been read out error memory. But this said that there is no contact between the motor control unit and the ABS control unit. I was then told that the ABS block is probably broken. The funny thing is that sometimes even if only very rarely both lights are off once and Mostly when the engine has been switched off afterwards. It is about a Twingo C06 BJ. 99 58hp. The fuses under the steering wheel are all OK and also the 30 ampere fuse in the engine compartment box. Would be very grateful for any help.