Trannnny Problems !!!

**OldTow** · 11-05-2009, 10:29 AM

We have an 06 C5500 truck with a 6 speed Allison tranny that is giving us a lot of problems.

We changed both tranny filters and the fluid as a general service procedure.

Now the tranny will not go into gear until you rev the motor a little, and when it does it really "bumps" and then will move out. Once it is driven for a while, it works fine. When we shut it off for a long period (overnight or even just a few hours) it has the same problem again.

Does anyone know the proper setting codes for this tranny, and have any idea what is going wrong

FYI, it was working just fine until the filter and fluid change

DuramaxSMOKE11 · 11-05-2009, 10:30 AM

are you sure you have the tranny filled to proper capcity?

Jscherbs · 11-05-2009, 10:31 AM

check fluid level, how many miles on the rig?

**OldTow** · 11-05-2009, 10:38 AM

In the beginning after the filter change it was filled and run way over full, but is at the proper level now.

It now has about 160,000 miles on it !

DuramaxSMOKE11 · 11-05-2009, 10:39 AM

tranny never over heated and did you find anything in the filters. sucks as metal filings?

Jscherbs · 11-05-2009, 10:41 AM

how often did you change the fuild/filter before the last change? you could have washed away some of the grit/chit holding things together causing improper enguagement and possible slippage. Do you ever notice a shift hesitation?

**scottdomine** · 11-05-2009, 10:46 AM

Could be NSBU switch, even though your symptoms are little different than that. Something to try though, they go bad often. NAPA has them for fairly reasonable cost.

**OldTow** · 11-05-2009, 10:50 AM

To the best of my knowledge we didn't find any foreign material in the filters or the pan, and the mechanic said as far as he can tell, mechanically it was fine. Didn't notice any slippage before.

When we got the truck it had 114,000 miles on it, so don't know about the service it had before.

**OldTow** · 11-05-2009, 10:55 AM

OK, now I am going to show you just how dumb "old cowboys" are. What is the NSBU switch??

**scottdomine** · 11-05-2009, 10:58 AM

Quote:

Originally Posted by OldTow

OK, now I am going to show you just how dumb "old cowboys" are. What is the NSBU switch??

Neutral Safety Back up switch. It is on the drivers side of the trans on the outside. Do a search and you'll find lots of info as they go bad regularly. Just replaced mine, about $60 and 15 min to fix. Had some of the same probs as you.