2004 trailblazer automatic transmission lost all gears while driving at about 60 mph (no reverse or low gears) what do you think the problem might be?
possible transmission problem on 2004 Chevrolet Trailblazer
The first check would be the fluid level. With the fluid level full try the shifter in all the forward ranges and reverse and see what works. If the trans won't engage forward or reverse you most likely have a major problem inside the transmission. If your Trailblazer is 4WD then there is a possibility that your transfer case is damaged or in neutral.