nsbu switch overheating

[dmax_3500]

just had a 2nd problum [this is the 2nd switch gm put in this trk],went from chi. to fla to drop a customers new toyota trk,everything fine until i got to orlando,then trans freewheeled and slammed into gear starting off from a light,then wouldn't shift out of 3rd gear[but shift ind on dash still all lit up ]i pulled over and scanned computer ' got a code [p0700 trans controller problum]i cleared cod and got 200 feet down road and it down shifted to 3rd again, i just needed to get to customers house and it was 7pm sunday night, so i pulled over again and poured a quart of water on nsbu and sprayed 1/2 a can on carb cleaner on it,i got back in trk cleared code again and took off ,trk shifts fine,could this switch be overheating?

[madmatt]

No, actually it's water intrusion. heres part of the bulletin....

Document ID# 1530039
2002 Chevrolet Chevy K Silverado - 4WD


--------------------------------------------------------------------------------

Slow or No Engagement of Automatic Transmission, No Start, Blank PRNDL Display, Flashing PRNDL, DTC P0708, P0872, P0847, P0875, P1711, P1713 or U1000 Set (Diagnose Condition, Repair) #02-07-30-011C - (Jun 21, 2004)
Slow or No Engagement of Automatic Transmission, No Start, Blank PRNDL Display, Flashing PRNDL, DTC P0708, P0872, P0847, P0875, P1711, P1713 or U1000 Set (Diagnose Condition, Repair According to Procedure)
2001-2004 Chevrolet Silverado

2001-2004 GMC Sierra

with Allison

[madmatt]

and actually the p0700 is just a mil request and doesn't exactly mean you have a NSBU failure. it shows up any time the tcm sees a fault and is usually accompanied by another code, like the p0708 NSBU code.

[jbplock]

Originally posted by madmatt:
... Proper installation of the "Front Shield" and "Rear Shield" are essential for proper repairs. madmatt,

Thanks for posting this info! http://forum.thedieselpage.com/ubb/icons/icon14.gif

Just curious... what are the Front and Rear shields referred to in the bulletin?

MP has a very nice article in the member's area that details how to R&R the NSBU switch (Click Here (http://www.thedieselpage.com/members/duramax/nsbu.htm)) It shows a splash shield that goes over the transmission selector shaft...Is this what the bulletin is referring to or are there additional shields that have been added? Thanks!!

smile.gif .

[dmax_3500]

yes,i know water getting in the switch is the problum,i've had that happen the last 2 times w/other codes,but somebody can try this if their stuck and trying to get somewhere,it was 20deg in chi and 74deg when the problum started again and i've got mud flaps since trk was new

[madmatt]

honestly Bill this is the only place I can find these shields mentioned. I'm assuming they are refering to the sheild thet slips over the selector shaft. I 'm not sure what their calling front or rear though. elsewhere in a bulletin it states the installation of mud flaps helps prevent repeat failures, but in my experience it doesn't mean the NSBU won't ever fail again.

[madmatt]

just found it...yeah thats what their talking about. the front is the large shield on the outside of the switch and the rear is what their calling the inner shield.

[jbplock]

madmatt, Thanks smile.gif