Intermittent loss of gear, temporary, no codes

[chaosrob]

2007 Silverado Classic 4x4 electric shift, 2500 crew cab, all stock except recent upgraded t case, 211000 miles

Weird thing happened today. 70 mph, cruise set, normal coolant temp, 125 trans temp, going to a bill and transmission popped out of gear and “d” light started flashing. Shifted into neutral and back into drive and everything was fine. Drive another 2 hours without issue. No cel No other symptoms. About two hours into the drive back, same thing except it found the gear by letting off the accelerator then pushing it back down. Now it will lose the gear again while normal city driving and there is a "whirr" noise, finds gear again by letting off the accelerator and reapplying.

T case was replaced about 3 weeks ago with an "upgrade" unit due to case rub, all electronics from original t case were swapped to this one. trans fluid/filter was also done at the same time and level is good without odd odor.

Suggestions? Input? Where should I start? My mind says it's the t case as I do not believe in coincidences but I could be wrong.

 

[Ron Nielson]

Check fluid levels trans and TCase to be sure the easiest thing has been verified.

 

[chaosrob]

Check fluid levels trans and TCase to be sure the easiest thing has been verified.

as mentioned above fluid levels are good but thank you for the reply

 

[1FastBrick]

Check the electrical connection on the back of transmission. Make sure it's not leaking fluid and that it's fully seated. Same with the speed sensor on the T-case.

 

[chaosrob]

Check the electrical connection on the back of transmission. Make sure it's not leaking fluid and that it's fully seated. Same with the speed sensor on the T-case.

Ty, checked them both and g2g. I think I may start tracing all wires back and checking for exposure, some of the loom looks pretty bad under there, maybe something has rubbed and is shorting. I would certainly think that would throw a code though

 

[BLACKMAX1]

I had a similar issue. I took the pan off and cleaned/reconnected the plug at the back of the trans, changed internal/external filter and flushed with new fluid and all was good. Since your T case was replaced I'd go thought the connetors on there as well.

 

[chaosrob]

Transfer case is bad, just ordered a replacement from GM. Not going to gamble with the aftermarket unit again, too much work and headache and the "warranty" is laughable as was their replies to the issue

 

[1TRIKHD]

Transfer case is bad, just ordered a replacement from GM. Not going to gamble with the aftermarket unit again, too much work and headache and the "warranty" is laughable as was their replies to the issue

What was the issue with the t-case?

 

[chaosrob]

What was the issue with the t-case?

apparently an issue with a rear snap ring causing movement that gave erratic speed signals