Newbie here. Intros latr. Have an 01 silverado duramax w/ allison. Last night engine light came on, out of blue, and trans seemed like it was stuck in 3rd. Called and cant get truck in till next week so looked online. Found a post on this and it sounded like my problem. Said sounds like Netural switch. So bought part number but new part has little port between electrical plug hook ups, that looks like a vacume hose connects to it. Old part dosent have it.





Also, can I move the nylon thingie so it lines up with shifter bolt(?) coming out of trans? theres a metal thing on there now(the new part) that looks as though its there to line up the nylon and bolt , that seems like you remove it once switch is in place. Problem is, nylon thing looks like it has to be turned in ordrer to line it up with bolt. Please, if anybody reading now respond or mail me, its cold outside!!!! THANK YOU< RICH

Let's see....
- You'll be putting the truck in neutral, so make sure you take the appropriate precautions when you raise it (wheels blocked, etc).
- If the connectors don't pull off easily, take the hair dryer out and warm them up - the potting sometimes melts in the old style NSBU's and the heat will loosen it enough to get the connectors out.
- Disconnect the shift cable BEFORE you try to loosen the nut on the selector shaft - otherwise you're looking at a broken shift cable. No fun to change. http://forum.thedieselpage.com/ubb/smile.gif
- Once you have the nut and lever off the shaft, just pull the two bolts that hold the NSBU to the trans and finesse the NSBU off. It's a tight fit around the front driveshaft, but it will come out of there.
- Next, make sure the trans is in neutral (rotate the shaft all the way clockwise for park, then two clicks CCW for neutral. The flats on the shaft should line up with the little diagram cast into the trans).
- The new NSBU will have a small piece of stamped steel on it - that is to hold the switch in neutral. Leave that piece on the switch and install the switch onto the trans.
- Tighten the two bolts to 18-21 lb-ft, remove the stamped steel piece, install the new shield, the shift lever, and the nut.
- Tighten the nut to 15-20 lb-ft, install the cable, plug in the connectors, and you're done!

IIRC the trans has to be in neutral when the NSBU switch is installed. The little metal bar on the switch is in place to ensure that the internals of the switch are lined up with neutral, so it stays on until the switch is installed.

THanks, I wish I read this first, cause I took the whole thing off while the shifter was in Park. Now what, Can I hook the cable back up without the switch and put it in neutral, and then remove it again and then install the new switch?


Also, what about the vacume port on the new switch, old one dosent have one. Again THANK YOU!!!!!!

Ratrace

Just take it back off and follow Jakes instructions ,,,
=>- Next, make sure the trans is in neutral (rotate the shaft all the way clockwise for park, then two clicks CCW for neutral. The flats on the shaft should line up with the little diagram cast into the trans).

I have no clue what your talking about as far as vacum port .... Never seen it ..... Where did you buy the switch at ....??

Mac

I believe that you can rotate the trans to neutral using a large crescent wrench, as long as you're not bound up on the parking pawl. I have NO idea about any vacuum port on the switch. What part # did you get?Edited by: Hound

OK I put the cable back on and shifted it to netural, and jimmyed the new NSBU back on. It was tight getting it over the trans bolt.


Put it all back together and it seems to be alright now, but engine light is still on. Read in manual it takes a couple of cycles for it to re program itself off. True?





As for little vacume port yes its there, at least it looks like a vacume port, small about 1/16th ID, right inbetween the two plug inputs, hell I dont know but maybe someone knows about this , I guess I should plug it for now, but no time...


Got he part from FRANKS GMC in Lyndhurst , 47 bucks with tax. Looks exactly like old one but is beige and has aforementioned vacume port.





Well, thats it. Man, thanks for the quick response. Have a few other questions about my truck but Im gonna read thru the site so I dont have to ask questions that have already been answered. Again, THANKS!!!!!!!

It is etrue the light will eventually estinguish .... You received a good price from a dealer compared to the rest that have been reported ...I was asking thinking you bought at a Allison dealer and perhaps it was for a different application,but doesen't seem likely .... Would be nice if you could snap a picture of the port for I've never heard of it ...





Welcome to the site ask away ...





Mac

I had to replace my second nsbu switch in just over 12 months last december, cost me 52 beans including tax got it from an allison dealer at 9:30 at night, no p/u truck dealer open that time of night, thank you GM for putting a real truck transmission in our trucks. No vacuum port on new switch.

This is what Rat Race is talking about. I just picked one up the other day and noticed it too.


http://www.dieselplace.com/forum/uploads/Z96_NSBU1.jpg


http://www.dieselplace.com/forum/uploads/A69_NSBU3.jpg


What do you think? Wrong switch? Plug it? Leave it alone?


Kevin

That's interesting as that is an electrical componet ....


Going to have to do some research on it ....


Mac

Just a guess, but do you think it may have something to do with the build date on the switch? It is 6/2/03.


Well, as I was typing this, I couldn't resist the urge to stick a straightened paperclip in there and see if it went anywhere. It does not appear to. Paper clip goes in about 1/8" and stops. Felt around and applied some pressure, seems to be sealed.


Kevin

Could it be a place for a screw to hold on a cover? What would you call it a screw reciever hole?

Could be a vent to help keep it dry.

You all see that skinny galvanized sliver of steel with the cicular part in the middle?

That's only for installation purposes. It holds the switch in nuetral. The idea is to place the trans in nuetral and install the switch that's also in the nuetral position. That way when you install the switch mounting bolts, the new switch will be "pre-adjusted" to the same position the old one was in. Once the switch is in and the mounting bolts are installed, discard it.

If you goof it all up, you can install it, making sure the retangular hole in the switch lines up with the flats on the trans shaft. Push it on. You'll notice elongated slots where the mounting bolts go. This allows adjustment of the switch contacts to syncronize with the shaft/trans position.

I goofed and all I did was center the slot. Worked fine. If it doesn't work right the first time, you have to do a little trial and error. DOesn't take long.

Just be careful crawling under the truck.. Edited by: hoot

Could it be a place for a screw to hold on a cover? What would you call it a screw reciever hole?


Could be, but doubtful. It even has a raised plastic area to hold a rubber hose on.


As far as it being a vent, I guess it could be. It does not seem to have a penetration into the body of the switch. I wonder if this switch is similar to another that Allison uses? They may just cast one body for all their applications and seal the port off for our apps.


Thanks for the heads up on the little metal strap, Hoot. My shift indicator started acting weird after we had some snow and about three days of rain. As soon as everything dried up it was back to normal. I am going to hold off as long as I can and wait for a warmer day to do the swap.


Kevin

Injection of potting material?

The 8.1 uses this trany. Something for it? Sure looks like a vacuum port. What doesn't make sense though, if it were a vacuum port used on the 8.1, you would have a vacuum "leak" when it was open. Maybe it's for extream use and they blow a stream of warm, dry air down a tube and through the switch for under water use on something like a Hummer to keep it dry? It would be under positive pressure so no switch going out in the slushy snow either.http://www.dieselplace.com/forum/smileys/Big Smile.gif


Steve


On edit: If the hole was open on some and used for something on another application, there would be more than one part number. Maybe it is for future use.Edited by: YZF1R