Hard reverse shift 2-3

[RossThompson]

My transmissions has started acting strange when shifting. I drove 500mi pulling a 7k lb trailer with zero issues. My wife and I drive the beach from South Padre Island to Aransas Pass, about 30 mi. I was running in 4hi and manual select 2 and 3, drove another 30 mi in 2 and D stopped the truck went in to eat. Get back in the truck, everything is still good. Drive back to Corpus on the highway 75mph and 30mi, went into town about 15mi of city driving. Go to put the truck in R and it bangs in real hard. Get back out on the highway and the tranny is shifting 2-3 funky now.


I drove 185mi today pulling my trailer with zero issues, tranny temps between 185 and 192. I reflashed the ECM and TCM with EFI Live, but didn't change anything.

I only run Nick's light tow in tow/haul or economy mode. I played with the his big tune for stock trans/stock turbo, but didn't beat on it. There haven't been any codes.

Any ideas??

 

[RossThompson]

A little more info. I drove 400mi today pulling my trailer in manual select and tow haul. No issues other than the hard reverse and 2-3 shift. Tranny temps averaged 190* with a high of 197* while climbing, climbed from ~100' to 3000'. No slipping or anything.

I'm wondering if its a valve body issue. I guess it's going into the local Allison shop here tomorrow.

Any help here???

 

[RossThompson]

NO help, opinions???

 

[sparepartsracing]

try replacing neutral safety switch any shift range inhibited messages...um sure someone will pop in and fix ya up

 

[RossThompson]

No shift range inhibited warnings, except when I put the t-case in N to see if the truck thought it was still in 4wd.

The hard reverse shift and the 2-3 shift not catching only happens in D, not manual select.

 

[RossThompson]

ok frustration is setting in...

I took the pickup to the tranny mechanic today. I backed out of the driveway and the tranny hesitated going in to reverse like it has been, I notice in the my way that the upshifts are all normal. I get to the shop, the mechanic drives it around and nothing, everything is normal, he pulls the dip stick looks at the level and smells the fluid and tells me there isn't anything wrong with it. Put about 75mi on it and nada didn't skip a beat...

I'm going to pull the pan tomorrow and see if there is anything in the fluid.

 

[blackdirtymax]

ok frustration is setting in...

I took the pickup to the tranny mechanic today. I backed out of the driveway and the tranny hesitated going in to reverse like it has been, I notice in the my way that the upshifts are all normal. I get to the shop, the mechanic drives it around and nothing, everything is normal, he pulls the dip stick looks at the level and smells the fluid and tells me there isn't anything wrong with it. Put about 75mi on it and nada didn't skip a beat...

I'm going to pull the pan tomorrow and see if there is anything in the fluid.

Why don't you try resetting the taps with efi and see if that changes anything? You could have picked up some bad learned shifting patterns

 

[RossThompson]

I did that late today, seems to be good. Still lazy/hesitation going into reverse.

Maybe ordering a diesel technology source tranny soon, I need to call David. He sent me a pm the other night on df.

 

[blackdirtymax]

I did that late today, seems to be good. Still lazy/hesitation going into reverse.

Maybe ordering a diesel technology source tranny soon, I need to call David. He sent me a pm the other night on df.

Sounds like a plan!!!!!:thumb:

 

[Mike L.]

I did that late today, seems to be good. Still lazy/hesitation going into reverse.

Maybe ordering a diesel technology source tranny soon, I need to call David. He sent me a pm the other night on df.

And if the new trans doesn't work you will of course have it diagnosed?

 

[RossThompson]

And if the new trans doesn't work you will of course have it diagnosed?

Not sure what else to do Mike. I've been beating my head against a wall since friday. I'm all ears if you have any ideas.

 

[MaxPF]

I gotta agree with Mike. Instead of finding another trans tech to diagnose your problem you instead feel it would be better to drop a bunch of coin on a new trans? :screwy:

It has been my experience (in the Phoenix area anyway) that most auto/light truck trans techs don't have a clue about the Allison, even though it has been around for 12 years. You need to find a shop in your area that has expertise with the Allison in GM pickups.

 

[RossThompson]

I understand what you and Mike are getting at. The Allison specialist here, service manager at inland truck (http://www.inlandtruck.com/) said there wasn't anything wrong with it, probably a good assumption he knows what he's talking about. However, I know there was something wrong with it; be it in the trans, TC or TCM. Other than inland truck, there isn't anyone here that know the allison trans, the dealers farm out all there allison work to inland truck except fluid and filter.

The reason I came on here was to get help diagnosing the issue, but outside of Blackdirtymax and David from Diesel Technology Source, there hasn't been any consructive use of this thread.

As of today, the tranny is shifting normal in all forward gears and the hesitation going into reverse has decresed but is still noticable.

As I stated earlier, I'm have open ears for any help.

 

[Mike L.]

Bring the truck back to stock and see what happens.
Seems you have done some wierd things like driving in 4X4 in manual mode. Playing with a big program and then taking it out. Reflashing the computers. All those things are going to affect trans shifting.

 

[RossThompson]

Thanks! I'll give it a try.