Allison Problems [Archive] - Diesel Place : Chevrolet and GMC Diesel Truck Forums

: Allison Problems


KWalk
01-24-2004, 05:40 PM
I have a GMC '03 2500HD Duramax with 26,000 kms (or 12,000 miles).


Several weeks ago, after driving through some snowed in roads (no deeper than 12 inches) I had a tranny problem.


First I was unable to manually select 3,2 or 1st (while in 2wd or 4wd) Putting it into drive was even a little stick. The selector would not move past D. Over several hours of normal use on the highway it became worse. Then a failure code came up on my gear indictor screen that said "RANGE SHIFT INHIBITED". At this point it started to slip in and out of gear. I stopped andI had nothing. A few minutes later I had Reverse, but no drive. It made an awful banging sound when I would try to put it in gear as well. The next morning it worked fine and was able to drive it to my GM dealer and they cleared the codes and said it was good to go, by my tranny oil was badly burnt. I changed it (60000 kms early!!!), but they had absolutey no explanation for any of this.


Today, while in 4wd in the city I had the same problem for about 10 seconds, and gone again.





I cannot get an answer from any "Goodwrench mechanic", but it seems like there are a lot of people who know what they're talking about on this forum. Does anybody have any similiar stories or some explanations/advice.

Mackin
01-24-2004, 05:50 PM
Double mint ,double mint incident ....


See here ->http://dieselplace.com/forum/forum_posts.asp?TID=4369&PN=1





Mac http://www.dieselplace.com/forum/smileys/Embarrased.gif

Mike L.
01-24-2004, 07:23 PM
It is your NSBU switch for sure.


mike

KWalk
01-24-2004, 08:49 PM
Mike:


So thats my Neutral Start Backup switch. The failure of that would obviously cause my tranny to limp along.


One question, why would it fail, then work good for several weeks. I am also curious as to why my oil was burnt (it was never heated).


You have any suggestions on what to do?





Thanks for the info!!

KWalk
01-24-2004, 08:52 PM
[QUOTE=Mackin]


Double mint ,double mint incident ....


See here ->http://dieselplace.com/forum/forum_posts.asp?TID=4369&PN





Mackin:


I am new to the site, is it frowned upon to double post messages to try and get more feedback? Whats up

gwmayes
01-24-2004, 10:28 PM
NSBU = Neutral Safety Back Up switch. Yours is black in color. Need to buy a tan one from an Allison dealer. About $50. The black one is not sealed very well. Water gets inside, corrodes the terminals and messes up the computer. I believe it fails-safe to 3rd gear only. If you "burnt" the oil you must have been working it pretty hard getting through that snow.


New switch, new oil/filter (don't forget the magnet) and you'll probably be good to go.

Mackin
01-24-2004, 11:21 PM
[QUOTE=Mackin]


Double mint ,double mint incident ....


See here ->http://dieselplace.com/forum/forum_posts.asp?TID=4369&PN





Mackin:


I am new to the site, is it frowned upon to double post messages to try and get more feedback? Whats up








Um wasn't meant as a dig, bud just thought somehow you missed the response from a GM Goodwrench Tech ... If I was to frown I could have just closed or deleted the new post ....http://dieselplace.com/forum/smileys/Embarrased.gif


If your oil is burnt, do an oil analysis your self or have the dealer do it .... Black burnt fluid is not normal ...


Enjoy the site remember best intentions are meant in my forum posting 99% of the time ... I'll reserve my 1% for the War Room ...





Mac http://dieselplace.com/forum/smileys/Big%20Smile.gif

Mike L.
01-24-2004, 11:41 PM
Did you guys know that after the shift lever moves past the D position that the manual valve no longer moves? Smoke and mirrors after that guys.http://www.dieselplace.com/forum/smileys/HiHi.gif The shift lever on the colum moves, the contacts in the NSBU move accordingly with the shift lever, but nothing is moving in the trans.http://www.dieselplace.com/forum/smileys/Big Smile.gif

dmaxalliTech
01-25-2004, 12:32 AM
Did you guys know that after the shift lever moves past the D position that the manual valve no longer moves? WHAT? Say it aint so!http://www.dieselplace.com/forum/smileys/HiHi.gif

hoot
01-25-2004, 09:32 AM
The shaft and detent are moving.... That's inside http://www.dieselplace.com/forum/smileys/Clown.gif