No 1st or OD Until Warm

[chd1287]

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.

[j cAT]

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 ..

[chd1287]

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.

[transman618]

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