trans takes off in 2nd and wont shift, had trans rebuilt by a friend he is real good he just lives so far away, he didnt see anything wrong when he took it apart, had to have it built anyway. he thought the ingtion key switch was bad i replaced it still doing the same thing, any help would be helpful.... ok here is what i have done and what i have found...1 st i just got the blazer with this problem of trans not working rite. i had the trans rebuilt by a friend who is a master gm tech. he took trans apart and couldnt find anything wrong, just had alot of miles on it, put a new kit with a new conveter in it, trans seems to be in 3rd. the 4x4 switch is not lighting up. checked the plugs are clean and wires are tight.all fuses are good, but the day time lights have a problem every time i put the fuse in the lights wont go off. someone pulled the fuse out why i dont know. i put a new ingtion switch harness on, still problem. i had to put a new park neutral switch on because part of the top part of the bigger plug has broke so i had a old 1 put it on but truck starts fine in park but not in neutral. i think switch is out of ajustment, i can get it to shift but seems to be soft, and in 1st gear i cant get the odmeter to go pas 10 mpg, shift to 2 nd and wont go past 20 mpg , 3rd wont go past 30 mpg, 4 th wont go past about 45 mpg on the odumeter, ok just done a lot of testing foumd out that the front wheels where not locking in gear ran the vacuum line right and looked at the 4x4 switch in the dash it was not hooked up, i plugged it in, its locked in 4 wheel low and it will not switch out. i think the 4x4 trafer case motor is bad, does anyone on here know how to check the voltage at the incoder motor of the tranfer case.

 

A stuck 1-2 shift valve or a broken return spring on the 1-2 valve can cause 2nd gear starts.

Can you get it to shift if you manually drop the shifter down? Are 3rd & 4th gears working?

 

i think its in limp home mode. but will the 3rd brake light in the rear of the truck up on the top being out could it cause the problem?

 

The third brake light isn't even remotely connected to the transmission.

 

i understand that but, i put a new ingtion switch and had trans rebuilt. i think now its electrial

a voltage drope or spike i`m thinking could put trans in limp home mod

could the tranfer case buttons not working be the cause. because thet are not on, i just got this truck, trying to fix it.

 

About the only thing that the transfer case does that modifies the transmission operation is tell the PCM that the transfer case is in LO range to alter the shift timing.

Are you having more symptoms that you aren't telling us about? A voltage drop/spike should be noticeable if it were to affect the transmission and really would affect other things as well.

How well was the valve body inspected during the rebuild?

Have you checked for power to the transmission harness?

As an aside, please edit your posts to include additional information. Rules are rules.

 

i had the same issue a few months ago. there have been issues with the ignition switch causeing that symptom. also something stupid to check is your ign/gau fuse see if thats blown. i just ghetto rigged mine to start in first gear as its a offroad truck only

 

update it was the encoder motor. putone on fixed problem