Cole, who died on 5 August aged 90, was best known as Cockney wheeler-dealer Arthur Daley in Minder, a role he played for 15 years from 1979 to 1994.
Dennis Waterman, his co-star for more than a decade, is reading a eulogy at the ceremony, which began at Reading Crematorium at 11:30 BST.
The upbeat song "I Could Be So Good for You" was a hit for Waterman in 1980.
Cole was "surrounded by his family" when he died at the Royal Berkshire Hospital, his agent has said.
His signature role, as the small-time crook who dreamt of bigger things, regularly drew audiences of 17 million for the ITV show.