One problem related to transmission failure has been reported for the 2002 Mitsubishi Diamante. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2002 Mitsubishi Diamante based on all problems reported for the 2002 Diamante.
My wife was driving on the interstate when the transmission failed and would no longer propel the vehicle. I have researched the problem and multiple people have had the same problem. I don't understand why no recall has been made. This is a very hazardous issue, especially if you are traveling on an interstate. She had to coast the car over and was rapidly loosing speed, a very dangerous situation. The problem is a faulty part in the transmission called a wave spring. In every f4a51 Mitsubishi transmission, this has been an issue. The wave spring breaks, bypasses the filter, enters the pump gears and breaks the pump, ending in transmission failure. It is a costly repair, $1800-$2000. It is a faulty design, and a better aftermarket wave spring was eventually engineered. This should be a recall.