Two problems related to automatic transmission cooler have been reported for the 2002 GMC Envoy. The most recently reported issues are listed below.
I have a 2002 GMC Envoy which has a destroyed transmission due to the well known (but unbeknownst to me) failure of the transmission cooling lines. This is a clear design flaw, as the routing is close to the catalyst. Besides the obvious safety concerns of an on the road transmission failure, the location makes a fire likely. The design flaw is documented in TSB pt-4722. I believe these vehicles should be recalled.
Service engine light illuminates, engine cooling fan engages, engine power greatly reduces and transmission shifts improperly. Loud noise from computer controlled engine cooling fan. Vehicle will not accelerate or shift properly when driving with fault. Fan clutch replaced, computer programming changed with no success of fixing problem. GMC refuses to buy back vehicle. Dealership indicates this problem is occurring on all 2002 GMC Envoy's at varying levels mine being worse case. Vehicle is unsafe for use in any traffic situation as the problem manifest itself rapidly with severe loss of engine power, loud noises from engine and poor shifting and acceleration.