The man driving the vehicle was able to escape unharmed and he walked to a nearby house.
Homeowner Francois Rossouw said he didn't catch the man's name, but said he calmly explained what had happened. He said the truck was new.
Rossouw said he was curious and rode his bike out on the ice to check.
"Some of the candled ice was blocking my view, so I pulled some of the ice out," he said.
"I laid down and looked into the hole and I could see the truck perfectly."
He said the truck is resting on the lake floor about 4.5 metres underwater. He couldn't see any fuel leaking out of the engine or fuel tank.
There is no word yet of plans to retrieve the truck.