I have a very unusual situation which has me baffled. 2 months ago a purchased a 2004 Jimmy ZR2 that had no 2nd gear. It has been my daily driver for that time as all that's required is to reach 3000 RPM and 30 km (yes I'm Canadian) and let of the gas and I get a perfect shift to 3rd. There are no problems with the transmission other than that. Perfect shifts up and down including down shifts other than that. I have made the rounds of the transmission shops who just want to sell me the complete rebuild. My knowledge of Blazers is as a 10 year owner of numerous ZR2s that I restore and sell. mechanics I know but auto trans I have always avoided the internals. I know 2nd and 4th share a band but 4th works great. No slippage. It even towers good. I was about to install a replacement transmission until i saw this old post during research here.
https://blazerforum.com/forum/engine...ve-fine-84099/
in that post which received no replies is the EXACT same situation. He replaced the transmission but had the same problem with the replacement,, still no 2nd gear. That replacement was then sold to his buddy and it worked fine in his Blazer. so clearly a replacement could only end me into the same situation. for any possible replies I can add that the code didn't show up until today and does not show up regularly in spite of the problem. I did swap the ECM from my 2004 Blazer ZR2 but it did not resolve the shifting problem. Is there a specific wire from the ECM that would carry the signal to complete the 1-2 shift only? If changing the transmission didn't resolve the previous post with the same problem and changing the ECM doesn't resolve it what else can it be??? thank you for any help.

 

I want to add to anyone who is going to mention checking fluid level etc that it's all been done. The trips to the tranny shops trying to sell me the $2,500 rebuilds as well. I have a replacement tranny but was stopped by the above thread link. It is the exact same problem and after he replaced the tranny it too had no second gear but worked fine after the same tranny was put in another Blazer. Yes I tried swapping te ECM and no change. The issue I can't seem to find any direction of research s what could cause the loss of 2nd gear electrical between the ECM and the tranny? Is there a 1-2 wire that controls that shift? As the code reads "Shift solenoid A stuck open" I'm stuck.

 

Have you tried replacing the shift solenoids?
You are probably feeling TC lockup instead of 3-4 shift, because Solenoid A Is required for 4th gear.

 

Here is your shift solenoid wiring diagram:




George

 

I have the code stating Solenoid A is stuck open. To shift to 2nd Solenoid A has to close. To shift to 4th Solenoid A has to open. I purchased a new Solenoid to replace A and hopefully it will be able to close to complete the shift to 2nd. I suspect the fact that it is stuck open explains why I can get 4th but not second.

 

I just found the 2 bolts from the 2 bolt side of the transmission manifold pressure thing that you plug the harness into. They were stuck to the pan magnet. Could that cause me to getting the shift solinoid "A" stuck open code and no 2nd gear?

 

massive fluid pressure loss to the pressure switch, yeah that might do it...

 

Does this leave the rest of the transmission working perfectly? That's my dilemma. With bands or otherwise there is usually other issues or gears. I pulled a ton of gravel the other day in my trailer without 2nd gear and 4th had no slip even going up the hill. It kicked down to 3rd halfway. It was a recently rebuilt transmission as well. With the previous code being "shift solenoid A stuck open" and A needing to close to shift to 2nd I am wondering if the wire that sends the signal to close in either the outer or inner harness could be pinched? The solenoid passed the 9 volt battery test and the rod was clean. No transmission shops here will put it on a scanner to check the current. It's a $2,800 rebuild or nothing. Their failure rates are atrocious afterwards as well. There are no more auto wreckers in Metro Vancouver as all cars go to China for recycle. A sad situation. Take your chance at a $500 Marketplace replacement of solve the problem. Is there no way to test solenoid A from the ECM plug with the same 9 volt?

 

By your included wire diagram can I put a stethoscope on the transpan and use the 9 volt on the light green wire to listen for the click I got when I tested the shift solenoid?

 

Dont put any voltage to PCM Lines unless you really know what you're doing, as far as the solenoid, the pressure switch possibly loosing pressure would cause different issues, i misread the thread it seems, if the solenoid is good then next step is to put it up on a frame stand/all the jackstands your local walmart carries, run it up into second gear GENTLY with all tires off the ground, and backprobe the harness at the Solenoid A Apply voltage line, see if you have voltage making it to the solenoid.