AC415 MMCX Message " Long Pulse Error" on master vote level

We have AC415 Controller and xA 4.1 in frontend. In one of controller we are getting MMCX message " Long Pulse Error" on master vote level on both sides. (In our case DO16.NE3) Changed Suspected Master Vote, TDI Card and connection unit, DO Card of both sides but problem Persists. Isolated and rebooted controller one by one of both sides. We have taken reference of safety maintenance manual. (attached) What could be the other Possible causes and solution of LONG PULSE ERROR Message. Thanks in advance.