His wife Ann told nzherald.co.nz today he would remain in the coma as he has at least one bleed on the brain, which has also suffered some swelling.
He also remains on a ventilator.
"The doctors can't tell us a lot but we think it is a good sign he was able to walk and talk," said Ann Cooney.
"And most importantly he was stable overnight.
"So we are now just hoping he keeps improving. They were going to take him out of the coma today but they are worried he could do himself some damage because last night when he first got to the hospital he was trying to move around and get up.
"But he might be able to come off the ventilator today."
Ann Cooney said her husband also had a lung infection, which was being treated with antibiotics.
While clearly shaken by the accident, she was quick to praise the safety vests which are compulsory in both equine racing codes in New Zealand.
"If it wasn't for Frank's vest we are sure he would have a lot worse internal damage."
Harness racing's accidents which require participants to be hospitalised are extremely rare in New Zealand, with the last significant one at Alexandra Park being in March, 2008. That was when Cambridge driver Tony Shaw was struck violently on the head by his own sulky after it flipped when his horse fell at full speed.
His injuries were life-threatening, requiring brain surgery and Shaw, a New Zealand Cup-winning driver, has not driven since, although he has made a full recovery.
Cooney is an enormously popular member of the New Zealand racing community, a quietly-spoken horseman noted for his gentle manner with horses.
He has driven well over 600 career winners and trains a small team at Huapai in West Auckland.
"We have had so many calls and offers of help it has been amazing, but for now we are just waiting," said Ann.
