Maddmatts
Member
The transmission cooling system is pretty simple. Hot fluid goes out one hose to a heat exchanger in the cold side of the radiator and the cooled fluid is returned by another hose.
The manual does have a flow test procedure but requires specialized equipment to carry it out: Chevrolet Sonic Repair Manual: Transmission Fluid Cooler Flushing and Flow Test
The manual does have a flow test procedure but requires specialized equipment to carry it out: Chevrolet Sonic Repair Manual: Transmission Fluid Cooler Flushing and Flow Test