I am having some troubles shifting, idicator light is not necessarily correct (shift from park to reverse, indicator shows 3 momentarily), also occassionally when I am parking, shifting from Drive to Park (after coming to a complete stop) the trans seems to shift pretty hard. I have read thru this forum and found that this could be an NSBU switch. I did run her pretty hard thru some deep snow about 5 days ago. Can anyone confrim or offer any other diagnosis? I am also getting an intermitten check engine light (could this be related?) And my final question is how difficult is the NSBU switch to change? (I dont even know where it is) Edited by: Rookiew/Dmax

Oh yeah, I can almost bet the farm that it's your NSBU switch. I changed mine last week-very easy.


The switch is on the drivers side of your tranny. Check weather or not it's the black one. Those ones aren't waterproof. You need to get the tan one p/n 29540479.


Hope that helps.http://www.dieselplace.com/forum/smileys/Approve.gif





On edit: Get it from an Allison dealer, you'll save big time.Edited by: duramaxdiesel

NSBU http://www.dieselplace.com/forum/smileys/Cry.gif

Seems all of the local Allison Dealers are out of stock on this particular item, wonder why that is? Hopefully I will have a new NSBU in a few days, meanwhile the Dmax sits (now it wont shift out of first when in drive)http://www.dieselplace.com/forum/smileys/Cry.gif. Will let you know what happens.


ON EDIT:


NSBU Costs


Local Dealership - $159.00


Allisson Dealer - $46.95Edited by: Rookiew/Dmax

New NSBU switch was installed yesterday, and now all is finehttp://www.dieselplace.com/forum/smileys/Big Smile.gif


Thanks to duramaxdiesel & Heartbeatcanada for your responses.

My indicator is not showing what gear im in it seems to shift fine I just dont have the little "box" to show what gear Im in.


Oh reverse seems to work, its just all the other gears and park. any Ideas.


Would it be the NSBU also?

That's another symptom of a failing or failed NSBU.

John

two days ago, my friends 2001 HD2500 with a 8.1 gas and Allison had to be towed because of the same symptons, --- yesterday -- my 2002 Chevy 3/4T 4x4 Duramax/allison -- did the same -- shift indicator lights went crazy, check engine light came on, "clunked" going into gear, -- would not shift -- stayed in one gear all the way to town -- 12 miles at 2800 RPM and 45 MPH -- no gear change -- tried haul/tow mode, -- tried 4x4 mode high & low -- could not get trans. to shift -- has to be something electrical!! Billy Bob

I just happend to take a picture of the NBSU on my truck when it was a week old. I hope this helps some guys at understanding what it is that they are looking at when folks give directions. I picture is worth a thousand words. A million if your frustrated. http://www.dieselplace.com/forum/smileys/Big Smile.gif





http://www.dieselplace.com/forum/uploads/NBSU_switch_Small.JPG