Two problems related to automatic transmission cooler have been reported for the 2006 Honda Ridgeline. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2006 Honda Ridgeline based on all problems reported for the 2006 Ridgeline.
Where the transmission cooling line attaches to the radiator, corrosion occurs in the fitting and this causes the radiator fluid to mix with the transmission fluid. The resulting problem is the transmission starts slipping and the transmission can fail completely. There is a well know problem with the connector that corrodes prematurely. Honda has not recalled this vehicle or issued a service bulletin but Honda repair dealers are well aware that this is a class defect with all Honda Ridgelines and Honda pilot vehicles. The unsafe condition occurs when the transmission starts to slip without any warning. There is no warning light that indicates there is a problem. In my case I pulled out onto a busy highway from a side street and the vehicle was uncontrollable because the transmission was slipping all of a sudden. The repair to my vehicle included a new radiator, new fluids and a complete flushing of the radiator and transmission 5 times. This repair cost me over $1200.
The cooling line for the transmission where it enters the bottom of the radiator failed due to galvanic corrosion. This cause a large immediate loss of transmission fluid.