Hello, I have a 99 S10 Blazer V6 4x4 with 106K miles on it. It always ran great until a couple days a go when it wouldn't down shift when you need more power for a hill or passing power. Fluid level is good and was changed about 10K miles a go. What might be the problem ? Would it be electronic or a vacuum problem ?

Thanks

 

not sure on your gen of blazer, but mine had the same issue until I adjusted the kick down cable.

 

99 is all electronic so no kick down cable.

Does it only do this when in OD? Or is it pretty much whatever gear you are in? Will it drop to 3rd if you put the shift lever into 'D'?