Willi Webber, who helped guide Schumacher to seven F1 titles during a 20-year partnership, said he was no longer on contact with his protege.
He said: “The Schumacher family seems to be afraid of me. I sent the family flowers and cards for his birthday but I got no answer. That makes me sad.
“There seems to be the fear that I would disclose something about Michael’s condition but I would never do that. I would even sign a non-disclosure agreement.”
He said: “I think they should explain to his millions of fans how he is doing.
“For some time now I’ve been saying that the Schumacher family is not telling the whole truth.
“But I’m biting on granite because for a long time my advice is no longer heard.”
Michael Schumacher’s home in Switzerland where he has been cared for since 2014
And the former manager is optimistic that the 47-year0old German will one day recover.
He said: “When I’m home alone and the phone rings I often feel that it will be Michael saying ‘Willi, how’s it going?’ Hope dies last.”
Schumacher’s accident happened on a family holiday as he was skiing with his son at the Meribel ski resort in the French Alps.
Michael Schumacher has not been seen in public since his 2013 ski accident
The keen skier hit the right side of his head on a rock and doctors operated to remove blood clots from his brain but some were left because they were too deeply embedded.
His condition stabilised after he was placed in a drug-induced coma from which he later emerged.
In early 2014 he was transferred from hospital in Grenoble to his palatial home near Geneva where he has been cared for ever since.
Mr Weber’s replacement as his manager, Sabine Kehm, has previously said: “Michael has always been very protective of his privacy, even during the most successful times of his career.
“He has always made sure there is a clear and distinct line between his public persona and his private one.”