I have been chasing an electrical problem in a 4L60E trans and finally realized that I was part of the problem. It seems it had a bad 2-3 shift solenoid , so I ordered a new one from an online parts house and put it in. Still no 2-3 shift. Checked continuity of all the related circuits and checked for power to the trans--all OK. Finally checked the resistance of that new solenoid and found it at 6 ohms thru the harness, rather than the 20 -30 ohms spec'd. Pulled it out and found 1.1 ohm at the solenoid terminals. The moral of the story is that for a part like this, taking an ohmeter to the part before installation (even better if it checked before it leaves the store) would have saved a lot of work and headscratching. Hope this helps someone to avoid a lot of hassle. With parts stores reluctant to allow a return on electrical goods, an in-store check would be a good idea.

Life is like a box of chocolates, you never know what you're going to get. Sure would be nice if you did know but quality control seems to be a myth these days.