'97 S-blazer, 208,000 miles, oringinal auto trans, fluid level ok and fluid condition looks good, i noticed the vehicle was extremly sluggish, like it was starting off in 2nd gear, didnt seem to have 4rth gear either. even when i tried to manually downshift into 1st below 20 mph, there was no going into 1st. drove it about 20 miles to my dads to use his scan tool, found 4 codes, po740, po753, po758 and p1860. about 1/2 way there it seemed to run better, i took it up to 90 mph (just to see if the catalytic converter was clogged) it seemed to have all 4 geasr afterwards and would manually shift into 1st. i cleared the codes after writing them down then drove it, seemed to function normally. dont know if it will come back and act the same or just drop dead in the street somewhere. its parked for the time being while i try to figure out what to do. im not sure if 1 componet would cause all this or if i have more than 1 issue, and its odd that it went away. i looked up the codes, didnt really point me a direction to start. i doubt my high-speed 2 mile drive fixed anything, but its odd that it worked correctly after that.

 

Check the ignition switch. 1997 ignition switch is unique to that year and is very well known to have "issues". Seemingly unrelated electrical stuff starts happening intermittently. https://blazerforum.com/forum/articl...-switch-33465/

 

It did have a new ignition switch put in about a year ago.

 

I've seen bad ones right out of the box! Just cuz it's new, doesn't mean it's good. Better check the circuits to be sure

 

Ok, thanks.

 

I've replaced 3in two years, the ignition switch is more than likely the problem..