The 4 wheel drive intermittently works on our 2005 gmc yukon xl, therefore you never know in bad whether, in a slippery situation, if its working. i understand that a sensor on these vehicles is failing. in fact the part is on back order, because so many are failing. this is a real safety problem. *tr
While driving our 2005 yukon xl 2500 series vehicle the service 4wd message will alert from time to time at which point the ability to continue in 2wd is not affected but the ability to transfer into 4wd hi or lo is eliminated. turning the car off then back on clears the error and systems are again operable. this was fixed before under warranty but the problem still occurs without warning. problem has occurred in excess of six times over the past two years since purchasing the vehicle new.