Chasing an Allison ghost

[BudTX]

Last winter when it got cold my truck would sometimes not move. The shifter worked fine, and would initally go into R, but then the shift indicator would blink (and sometimes disappear), the truck would act like it was in neutral and the RANGE SHIFT INHIBITED message would show up on the DIC.

No codes, and no CEL.

I called the 'way out-of-town tranny builder, who would not return my call. His phone answering toady was no help. :nonod:

I decided to replace the NSBU switch (purchased at a bus repair garage that services Allisons), and the problem seemed to go away.

Fast forward to this year, again, only when the temperatures are under 25 degrees F or so.

Same problem, and same message, but sometimes there is no DIC message and the CEL comes on. The code is 0841, indicating a valve issue in the tranny.

I can clear the code and coax the truck to finally go into gear. Once the tranny warms up it runs like a champ.

I can't figure out why this is only happening in the cold. There is no ice or moisture on the NSBU switch, and the truck is garaged when not driven.

Batteries are new, grounds are clean, tranny fluid level is in the middle of the crosshatch when hot, spin-on is new.

Any ideas - ?

 

[BoostN]

Last winter when it got cold my truck would sometimes not move. The shifter worked fine, and would initally go into R, but then the shift indicator would blink (and sometimes disappear), the truck would act like it was in neutral and the RANGE SHIFT INHIBITED message would show up on the DIC.

No codes, and no CEL.

I called the 'way out-of-town tranny builder, who would not return my call. His phone answering toady was no help. :nonod:

I decided to replace the NSBU switch (purchased at a bus repair garage that services Allisons), and the problem seemed to go away.

Fast forward to this year, again, only when the temperatures are under 25 degrees F or so.

Same problem, and same message, but sometimes there is no DIC message and the CEL comes on. The code is 0841, indicating a valve issue in the tranny.

I can clear the code and coax the truck to finally go into gear. Once the tranny warms up it runs like a champ.

I can't figure out why this is only happening in the cold. There is no ice or moisture on the NSBU switch, and the truck is garaged when not driven.

Batteries are new, grounds are clean, tranny fluid level is in the middle of the crosshatch when hot, spin-on is new.

Any ideas - ?

My friends LBZ does the same. At one time Mike told me a bad pressure switch manifold. But....

 

[Mad Maxx]

Maybe there IS Moisture in the Connectors, and when it gets that Cold Out, it Freezes, and makes the Connection not that Good? It's atleast worth a Shot to Unplug and Blow them Out.

 

[Ed HD]

Use WD-40 to clean any moisture out of the connectors. This is the exact reason it was invented.

 

[THEFERMANATOR]

I also found where Kat posted a TSB regarding this code as possibly being caused by the wiring harness under the hood getting a rub hole in it from the power steering pulley. But the bulk of them seem to either regard a loss of prime, a sticking valve in the valve body, or a failed pressure manifold switch.

 

[RI Chevy Silveradoman]

I know there was a new and improved NSBU switch. Is it possible that you got an old switch for the replacement? Thus giving you the same problems. My Allison has done this also, once or twice.

 

[BudTX]

I have the new model NSBU switch.

I suspect that the problem is in the PSM. There is a good Alli builder about a 2 hour drive from me. He gave me his cell number and told me to call him the next time that this happens. I only drive the truck a day or two each week, so at least I am not stranded without a ride if it needs to go into the shop.

Thanks for the replies and suggestions. I will keep you posted.

Bud

 

[BudTX]

I think it is fixed!!

By way of back story, I initially (in December 2009) called the builder that put together the transmission for me in 2007. His phone staff told me that he was unavailable, so I left a message describing the symptoms (transmission would not engage when cold, CEL, RANGE SHIFT INHIBITED message, etc.) When I did not get a call back after a few days, I called again. The person answering the phone said that I needed to replace the NSBU switch. I ended up doing so as outlined in that thread referenced above.

I only had 1 other repeat issue last winter that I wrote off to a single occurrence.

Fast forward to this winter...

Every time that the temperatures get below 30 degrees or so, I have the exact same symptoms. After getting tired of dealing with it, and not being inclined to throw another NSBU switch at it, I called Tim Hecker with St. Joe Diesel and set up a time for him to take a look at my tranny.

It was not the NSBU switch. What I had been led to believe was a full Transgo kit my original transmission was not, as the boost valve was stock and had worn a ridge on the end that was hanging up, causing my problems. He also found problems with fit and wear in the clutch plates.

Tim carefully went through the entire tranny and got me back on the road again. The symptoms have been addressed, and the torque converter locks up a lot more decisively than it did before.

These guys do good work!

 

[RI Chevy Silveradoman]

Good to hear Bud!

 

[btfarm]

Original builder = ripoff

 

[BudTX]

Original builder = ripoff

The lesson for me is that internet reputation does not necessarily mean quality work.

I feel like that old German proverb: "We grow too soon old, and too late smart."

 

[Mad Maxx]

Original builder = ripoff

That's why when I got mine done, I Asked for every Part back that they took out / replaced. Just so I knew exactly what they Changed, and that everything I gave them went In.

 

[SfcJones]

Another reason why I will go with SunCoast......Pepp had hiis done and no issues were reported (or atleast I haven't heard any)

 

[Pepperidge]

Another reason why I will go with SunCoast......Pepp had hiis done and no issues were reported (or atleast I haven't heard any)

no issues here...and I beat the heck out of it at the track...

But When it comes time to refresh it, Steve and I will do it ourselves with MikeL parts...

 

[trotorx2]

The lesson for me is that internet reputation does not necessarily mean quality work.

I feel like that old German proverb: "We grow too soon old, and too late smart."

PM sent

 

[Pepperidge]

The lesson for me is that internet reputation does not necessarily mean quality work.

I know the feeling Bud...same one got me too

to clarify: I am not talking about my SunCoast V just some other work performed by the person Bud is referring to...

 

[trotorx2]

This isn't making me feel any better!

 

[Pepperidge]

I know the feeling Bud...same one got me too

to clarify: I am not talking about my SunCoast V just some other work performed by the person Bud is referring to...

This isn't making me feel any better!

clarification made in above post...

 

[Mike L.]

The lesson for me is that internet reputation does not necessarily mean quality work.

I feel like that old German proverb: "We grow too soon old, and too late smart."

WOW.
Sorry this happened. This kind of thing tend to make all of us look bad.

 

[BudTX]

WOW.
Sorry this happened. This kind of thing tend to make all of us look bad.

I am still kicking myself for not seeking out a way to get to sunny Southern California 'way back when I was wrestling with where to go for that tranny build.

The good news is that the truck runs great, the tranny clicks through the shifts like it never did before, and the TC now locks up decisively. It is a blast to drive!