I've searched a good but and haven't really found anyone with an issue like mine so hoping someone can help out. Truck is a 2000 rcsb with an lq4 and a 4l80e. Very loose no name 3400 stall. I took it to get a retune yesterday because it was just hanging on the Rev limiter at full throttle. He dropped the shift points and still sitting on limiter. So we took a drive and whenever he would command 2nd there was nothing. Just like going to neutral. It will peg the limiter going first to 2nd or when at full throttle and it down shifts. I can pull the shifter down to 2nd and it pulls fine in 2nd. I can start out with shifter in 1st. Does fine. Bump to 2nd. Does fine. Run 2nd out to around 5k rpm and bump it to third and it's like neutral. Truck also skips 2nd when just normal cruising. Holds 1st long enough to go into 3rd. So I'm kind of at a loss. Trans had a transgo in it until last week. Same issue. I thought maybe I had messed something up with the install so I pulled that valve body and put a stock one in which is what's in it currently. Also tried a stock converter. Same issue.

 

With both the 3400 and stock converters you're hitting the rev limiter when in "D"?

If you select 1-2-3 the gears work?

 

Read through this as it sounds familiar.

https://www.performancetrucks.net/fo...issues-544324/

 

Not really sounding like my issue. Yes it hits limiter with either converter and either valve body. In D my shift pattern is 1 3 4 lockup. In 3 it is 1 3. In 2 it is 2 only. Doesn't shift to 1st at a stop. 1st is 1st. I can start in first and Rev it out to 5k. Bump to 2nd. It shifts run it to 5k. Bump to third and it's like neutral until I let off. If I am in D and command it to hold 2nd there is nothing. Like its in neutral.

 

I'm having the same exact issue, or if not the same, pretty damn close. I have another thread trying to figure it out as well.

Check for play in your PRNDL switch and make sure the slip between the selector shaft of the trans and the plastic gear of the switch isn't causing the PCM to think it's in another gear... This helped my issue A lot with shifting manually, but it's still not wanting to hold in second with the shifter in D3 or D

 

Justin with blackbear did my in person returned yesterday and we went through all parameters on the laptop and electrically everything is showing to work as it should. Solenoids and the nsbu showing it's in the same position as the shifter.

 

Overrun clutch is used in manual selection in conjunction with the forward clutch. If it works manually and not in D then your forward clutches can be bad.

Others better than me know more.

 

That would make since. Guess I should get prepared for a tear down.