DiscoTA

I rebuilt a 1994 4L60E last march for a Buick roadmaster. Drove the car about 10,000 miles without a single trans problem. Then one day, no first gear after coming to a stop. If you shut the engine off and restart it, it will have first gear until it shifts into second. Then no first gear. I can manually shift to first and goes right in. I'm not getting a check engine lite and everything electrical seams ok. I tried changing out the valve body with a known working one and still the same problem. Anyone out their with some ideas what could be wrong or broken? The fluid looks like new and no metal in the pan.

FLT

iTrader: (1)

Check your 1-2 accumulator piston for cracks. I had a similar problem once on the trans dyno when I forgot to install the accumulator seal. The reason it did this is the forward clutch oil was getting into 2nd gear circuit due to the leak. It did exactly what yours does. Unfortunately I did put a couple skids in the band before we found it. Also you might have an A solenoid/1-2 solenoid that is not working properly. I would first check the acc piston. Then with a scan tool verify that the solenoids are commanding first gear when coming to a stop. Both shift solenoids should be energized for first gear. If they are not then you have another issue other than the accumulator or the solenoid. If both are commanded, I would replace the solenoid and go from there. Not sure if you reused the solenoids with the other valve body or if they were a different set. Just a thought. Vince