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Discussion Starter · #1 ·
My first post here, hope I am in the right spot. Sooo I have this nsbu switch that I am going to install my self today and was wondering if there was any concerns as to how to install the switch, things to watch out for, and when done will the trans work properly or do I need to take it to a Chevy dealer to clear the codes? Any advice would help a bunch, thanks Dino
 

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First, welcome Tackman. You're in the right place.

Couple of things if you have an older truck with the black, two connector NSBU. The potting material that holds the pins in the NSBU will sometimes run and ends up gluing the connectors in place. So, if they seem hard to get out try heating the connectors up with a hair drier and gently pull on them. If the selector shaft coming out of the trans looks corroded you may want to clean it up with an emery cloth to make it easier to slide off.

Most importantly, make sure to follow the directions on aligning the NSBU in Neutral. If it's off it can give you all sorts of problems.
 

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Discussion Starter · #3 ·
Thanks Machinator, this is on a 02. Yes it has the two connector NSBU. And I got the switch shiped to me from Allison, it came with no directions, so how do I go about aliging the NSBU in neutral???
 

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The switch should have come with a metal piece that goes over the hole for the selector shaft. This holds the switch in the Neutral position and will align it onto the shaft.

To install it correctly you need to have the transmission in Neutral. Block the wheels, disconnect the shift cable, remove the lever, turn the shaft clockwise until it stops then turn it counter-clockwise two clicks (that's Neutral), and slide the switch on. The tangs on the metal piece will align with the flats on either side of the shaft. Once it is on, bolts it down, remove the metal piece, and put everything else back together. You should be good to go.
 

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Discussion Starter · #5 ·
The box held two items, the switch with a metal backing plate attached , and a black plastic piece that looks like a misshaped cone?
 

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Discussion Starter · #8 ·
OK I installed the new switch as described above. Now my shift indacator lights work in the dash but trans. still only runs in third and reverse. When put into D the trans engages very hard. I know my spelling sucks!
 

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Sounds like the trans is going into default (i.e. third and reverse only). Could be a few things: It might be misadjusted slightly, connectors may not be seated all the way, or a pin or terminal could be bent.

If you haven't done so I'd pull the connectors off and take a look at the terminals and the pins in the NSBU and make sure everything is good. Your problem is probably in the 4-way connector as that's the one the TCM uses primarily.

Do all seven positions on the PRNDL light up?
 

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Can you tell from the possible marks on the old NSBU that it is close to aligned? Does it clunk when going into gear? Another sign of misalignment

Shutting the truck off with key fully off might take it out of default,by letting it set for a few minutes.

Otherwise it could be a faulty switch to bent pins making poor contact
 

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If nothing looks obvious you might want to try putting the old switch back on (providing it still works) and see if that makes a difference. If the old one works it may be a problem with the new switch. If it doesn't work it could be a connection problem.
 

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Discussion Starter · #13 ·
Will go back out to the shop and see if switch is in alignment? Must be why one of the bolt holes was sloted? And will check for bent pins, the plug ins went nice and smooth Thanks Dino
 

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Yes, there is some play to the switch. You might even try comparing the witness marks on the old switch with the new one and adjust it by eye if it looks off.

Good luck!
 

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Discussion Starter · #15 ·
OK SOOO who do I send the check too, that is for saveing me 250$ for not haveing to take it to the dealer!!! I took the new switch off and looked at the pins...all ok there and reinstalled switch, lined up the new switch just like the old switch and wham bam the truck runs again, just moved the switch on the slots just a tiny bit and it works . 4MS like this and Snowest are great, thanks to all who helped me out. Dino
 

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For future reference, when you are at the Allison dealer buying the switch, you can ask them to print out Service Information Letter 32-1K2K-01 which has instructions on how to properly install the switch.
 
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