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View Full Version : 02 duramax nsbu switch


chevfanatic
06-22-2014, 10:58
I need help here. I have a 2002 chevy duramax 2500. Allison. the dash gear simbols didn't line up when its in gear except 1st and reverse. then it started making a really rough clunking noise when going from neutral to drive. I looked in to it and figured it was the nsbu switch. so I spent over 200$ on a new one,. now the lights line up. but it still makes the clunking noise from neutral to drive. and im pretty sure its stuck in 3rd gear. I need help. (neutral safety backup switch)
rapidoxidationman
06-22-2014, 16:56
Loose drive shaft u-joints?
chevfanatic
06-23-2014, 06:40
no. everything is tight. tcm maybe?(transmission control module) its a 800$ part new thought. I heard they posbibly need to be reset after replacing the nsbu switch.
chevfanatic
06-24-2014, 16:45
this forum is worthless. thanks for nothing *******s.
DieselDavy
06-25-2014, 10:41
Woow down there Pardner! Give us a chance man... First of all, it takes a few days for some of us here to see your post. Most of us work for a living. Second, I'd take a second look at Rapid's suggestion. I've changed more than my share of U-joints in my time and am sure I know how to spot a bad one. BUT I actually took apart my transfer case once looking for something loose that would make the noise you are talking about only to find that the rear U-joint was shot. Since the noise was "clearly" coming from the transfer case area, I knew it couldn't be the rear U-joint and paid it no mind as I removed the t-case. Needless to say, I won't make that mistake again!
Another possibility might be play in the rear diff. The high mile truck in my sig line had significant play in the differential after so many miles and actually turned many degrees before engaging fully. This exerted excess stress on the U-joints and necessitated U-joint changes every couple of years. Take a second look and let us know how it turns out.
DmaxMaverick
06-25-2014, 10:57
If it is "stuck in 3rd gear", then it's in "Limp Mode", likely for a transmission issue. Check for trouble codes. If all you get is P0700, you'll need a more capable scanner to read TCM codes. If the condition is corrected, it may take a couple/few warming cycles for it to self-clear. If it continues in Limp Mode, the condition likely still exists, but you'll need the code to know what it is.

2-piece or 1-piece drive shaft?