So I have had this truck 1 yr now and recently the tranny feels like it is staring to hit gears harder. Especially when slowing to a red light but then accelerating as it turns green, it down shifts then feels like it gets confused and finally hits up a gear. I have 69K miles and figure the tranny fluid and filter needs changing. Any thoughts?
AWD Transmission acting strange on 2007 GMC Sierra Denali
by dhettich in Torrance, CA on November 04, 2010
ANSWER by patrick mannion on November 04, 2010
Sounds like a transmission problem, cheapest thing to try is to change the transmission oil drop the transmission pan and inspect for debris and change the filter.
ANSWER by denali lover on January 09, 2015
It soundsnlike you are dealing with a bad transfer case. I would start there. Either way you are looking at a 1000+ in repairs. I just replaced the transfer case in my 2003 sierra 1500 Denali, myself.