Originally Posted by surreybrad

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.