Diablosport Forums

Hey guys, ive been having this issue with my trans for a while but cant seem to put a finger on it. The dealer i work at thinks this is a tuner issue but we cant get it to happen all the time.

The truck will at any random rpm sometimes forget to shift into 2nd then command a hard second gear shift. Gm has a tsb on the issue but they tell me to replace the tcc harness under the valve body. The tech seems to think we would just be throwing parts at it and wants to make sure that the computer is commanding the right thing or that the trans is fouling up. That way he knows what to replace.

I just want to get this fixed but since it doesnt happen all the time im stuck and dont know where to start. If you guys can help that would be great.

well, if you restore the stock tune, does it still do it sometimes??

if so, then that tells ya right there that it's not a tune issue...

Is it temperature specific? Is it after a drive or is it any random time?

It sounds to me like the 1-2 shift solenoid or the 1-2 shift valve in the valve body is sticking at time's. It's possible the shift valve has a burr on it or there could be debris in the shift solenoid.

well Lew your right i will take the tune off the truck and see if it does it, it just happens so intermitenly that ill have to wait about a month till it shows again. ....and thanks rage i was just pricing those out, seems pretty cheap only about $25. ill check it out.

lew if this is a tune issue what do i need to give you guys to help diag this issue. I assume a data log. If i could get a log from what my dealership calls a vdl (vechicle data logger) can you do anything with that file, or do you need predator stuff

would need to be a predator log, so it could be opened and exported with the dataviewer...

if it appears to be a tune issue, then we'll cross that bridge when we get there... would have to have johan take a look at it, and also find out exactly what you'd need to log...

but I don't think it's a tune issue... I haven't heard of anyone else having this issue with theirs...