pull the trans fuse with a test light one pin wont have power, run a 14 gauge fused wire from the battery to the pin with no power. if all works well you have a bad ignition switch gm has a tsb for bad ignition switches.

 

Hello Performa,I have talked to you a few times about po758.My 99 trans am does not always do it but it happens po758.I have changed the solenoid,checked and cleaned the plug going into the tranny and checked for any bare wires,changed out the pcm with all the same info,changed out the igntion switch,the last thing I did was the pcm it ran fine all day no problems this morning I started the car to bring it out and wash it and I was in reverse backing out then put it in drive to pull it up and back again to park it and ses came on and stuck it in limp mode.Know when this po758 happens it usually did it after driving it for awhile.Like I said new pcm installed 11-12-11 and drove fine all day 40 plus miles.Then this happens.I am so over this **** and want a resolution.I know you are very knowledgeable on this stuff.Can you please help.I am desperate and I knew in the back of my mind it would.Is it grounds? If so where are they?

 

I would think maybe grounds try running a couple new ones from chaisis to battery and engine

 

I checked the code and it is not po758 so I guess the ecm swap worked for po758. it is now po785 3-2 solenoid.

 

Hello again Frank,

Well its over a year now and im still having issues with 2-3 solenoid.As you can see from my post all that I have done.Last time we talked you gave me instructions on what wires I need to run to bypass any short in the 2-3 solenoid wiring and I did that.The car does not do it as much as it used to but still does it anywhere from 2-3 times a week or sometimes not for a month.I do notice it does it when im hovering around the 35 to 50 mph where it wants to shift.It either shifts fine or it will start to act up(bucking)and then go into limp mode.If im on the highway no problem but around 35-50 it can go either way.I know gm had some kind of shifting issue around the parameters and that it could be deleted but by buying a new transmission.When it does act up if I shut it off while coasting it will go away .When it does go away it either goes away untill next time it deciedes to or it will do it again or it will go away for a few minutes and do it again.Frank I work at a shop on the weekends and have tried all the possible glitches and still can not stop it.I even make sure the tire pressure is on spot so it will not throw off the speed sensor .Again I ask for some guidance.
Thank you
Kevin

 

I would first of course check or replace the 3-2 solenoid but its also possibly again still a wiring issue of some sort but one thing at a time.