my blazer started shifting hard the other day out of no where!has fluid,what should i check next? only from 1st to 2nd...if i rev to 2600 rpm and let off it shifts but thats it...please help

 

Check out the Tech Article (DIY) section (link in my sig) for a thread on common 4L60E problems.

 

I know mine shifted really hard when the ECM was in limp mode. Hopefully the DIY section will help you out.

 

Is it idleing high aswell? If so its probally the TPS.

 

Mine does the same thing, but only after driving for a lil while and its throwing a CEL, code P1870 I had read that replacing the ignition module would take care of this, well, I replaced it last night because I had a bunch of other codes the day before and couldn't get the key out, well, replacing that solved all the other issues but I still have the hard shift 1-2 issue. But again only after driving for a little while. Once it does it if I shut the truck off and let it sit for a min, start it up and drive its fine, doesn't do it anymore until I drive for a little while again, hope someone can help!

 

ok tps meaning Throttle Position Sensor right?where is it on the truck?no there is no high idle....

 

Yes the throttle position sensor. It being bad can cause a hard 1-2 shift and you would probably have a hard time with overdrive.

Its right on top of the engine next to the throttle body. It's circled in red in the attached picture. A new one will probably run you about $35.

 

That picture is of the MAP sensor.... The TPS is located on the Throttle body.

 

As far as mine goes, if the tps is bad would it throw the p1807 CEL? I should probably start my own thread but were having the same issue. I don't have any issue with overdrive though. I gotta get this fixed asap as my inspection is up at the end of this month and with the CEL, no inspection for me!

 

i'm pretty sure my overdrive is not working right.is the TPS under the plastic intake right where it comes from the top of the throttle body on the drivers side?