No 1st or OD Until Warm

When I start my 99 2 door Tahoe in the morning it shifts really hard from 1st to second, then just fine into third but will not shift into overdrive. Then I have to manually shift between the two working forward gears (second and third). After it warms up completely and I shut it down for about a minute and restart it, everything is fine. If it cools enough, it will once again not shift into 1st or overdrive. This started after the sun shell snapped and I had it rebuilt. The guy I had rebuild it said he had to install a sleeve for one of the checkballs. Not sure if incorrectly installing one of these could casue this. I've checked the wiring and it seems fine. I pulled and replaced all the connectors. The code thats coming up is. P0785 Not sure if I should replace the solenoid first or where I should start.

find another tranny shop that knows what their doing ...after the tranny is removed and inspected , also considering the age/mileage the experts can determine whats needed and if this is repairable...


how many miles? how often did you own/service this transmission ? how did you use the vehicle towing ? overheating ? fluid loss ?


ya in a perfect world you could get the exact answer to YOUR question ...with out even looking at the tranny ..

Its got 155k. No other problems with the truck. No leaks, tranny fluid level is spot on. Trucks runnin like a top after it warms up. I'm the third owner, but as far as I know this was its first rebuild.

Its shifting like that because its in limp mode. You need to ohm out the 3-2 solenoid and see what kind of resistance you are getting. 9-14 ohms. any more or less= replace solenoid. Check wiring real good sometimes trans techs damage the harness during rebuild or break connectors when installing pan.


transman