Transmission problems

[Fireguy1]

My transmission is causing me some grief. I hope someone can give me some ideas as to what may be happening. The transmission was rebuilt about 5000 miles ago. The Yukon has been sitting for about 7 months. I just replaced the motor that had a blown bearing. My problem is that when the truck is in OD it shifts through 1 - 2 then shifts into neutral. I drove it in first .. no problem, second .. no problem, put it in third and it goes to neutral including OD. So I have reverse, first and second, but no 3rd or OD. Any ideas?? Please help if you can. I have no codes coming up.

[retorq]

Who rebuilt it?? Did it work before when it was first put in??

[99Yukon_Z71]

First check fluid level!! If the fluid level is low, you will cause a lower line pressure for the 3-4 clutches and cause them to burn out!!!! If level is OK then consider the clutches burnt. Smell the fluid, if it hasa weird clutchy smell or is a brownish color, consider the clutches burnt. Had this happen to me. If you keep driving it, a code might appear, but you will cause more damage to the trans.

[SunlitComet]

+1 what you describe is the 3-4 clutches gone bye bye.

[Fireguy1]

transmission fluid is full, clear with no smell. Took it for a ride today,,, shifted through all gears 1 - OD then after warmed up dropped to nuetral. Yukon was parked for 10 months. Transmission worked fine before that. It has about 10 - 12,000 kilometers on it since it was rebuilt. This morning when it was cold it shifted through all gears very smoothly. Has me stumped.

[SunlitComet]

that would lead one to think that thermal issues are causing fluid circuit leaks or wire breaks.

[Jaycenk]

It's been under a year since rebuild then take it back to who ever rebuilt it. It may just be a set of bad electronics in the trans. Some times these rebuilders try to save their selfs or maybe you some money by leaving the original electronics in them and it almost always leads to problems.