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Gear indicators not working? Not shifting right?

Sparky8370

Sparky8370

Do chickens have large talons
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I'm putting this here because I haven't seen an allison forum yet. If one gets created the mods can just delete this part and move it if they'd like.


Last year I had the nsbu switch on the side of the tranny let go. The old version is black and susceptible to damage. There is an updated part that is tan that is supposed to be better. I haven't had any problems with mine since I replaced it. The part number is 29540479 and you're better off getting it at an Allison dealer.
Mine was a two plug deal, allison went to a single plug later, and then put them inside the tranny. So if you have a newer one the part number may not be the same. Just look and see how many plugs you have.

With mine the resin inside the switch had heated up pretty good and pretty much bonded the switch and plugs together. I just broke the old switch apart carefully so I didn't damage the plugs, and scraped all the resin off the contacts in the plugs with a dental pick. I then used elec contact cleaner, di-elec greased them, and sprayed silicone electrical connection waterproofing on the outsides.

Hope this can help someone out. Feel free to add to this if you have more info.
 
no, higher current flow than it was designed for. As the connection got worse from corrosion and resin the current draw was even more. Or at least that's what I'm assuming. Tranny runs cool like most of them do.
 
Sparky8370 said:
I'm putting this here because I haven't seen an allison forum yet. If one gets created the mods can just delete this part and move it if they'd like.


Last year I had the nsbu switch on the side of the tranny let go. The old version is black and susceptible to damage. There is an updated part that is tan that is supposed to be better. I haven't had any problems with mine since I replaced it. The part number is 29540479 and you're better off getting it at an Allison dealer.
Mine was a two plug deal, allison went to a single plug later, and then put them inside the tranny. So if you have a newer one the part number may not be the same. Just look and see how many plugs you have.

With mine the resin inside the switch had heated up pretty good and pretty much bonded the switch and plugs together. I just broke the old switch apart carefully so I didn't damage the plugs, and scraped all the resin off the contacts in the plugs with a dental pick. I then used elec contact cleaner, di-elec greased them, and sprayed silicone electrical connection waterproofing on the outsides.

Hope this can help someone out. Feel free to add to this if you have more info.
Click to expand...

So should I clean up the old one or buy a new one?
 
The plugs on mine had to be heated to get them disconnected. There is a sealant on the connectors. They plugged back in OK. This is from the mech that replaced it and I believe him since I know him.
 
A heat gun should allways be used to remove the connectors. Make life a lot easier.
 
so what would cause a truck to have these symptoms, but not be the NSBU??? my dad's '02 still isn't right, even though we put in a new NSBU last night! It still blinks in reverse sometimes and shifts hard from reverse to drive and vice versa.
 
Moisture and electronics don't mix!
If the NSBU wasn't too old, I'd remove the electrical plugs, inspect pins/plug for damage, dry it out with a heat gun, coat with dielectric grease, and try it again.
I always carry a spare.
 
That sounds like the NSBU but the shifting hard could be filters. Has the trans been serviced regularly by changing the external filter and flushing the trans which also flushes the internal filter?

If not then a complete trans service including the internal filter should be done. It also is the symptom of a sticking valve body.
 
Tom Cobb said:
That sounds like the NSBU but the shifting hard could be filters. Has the trans been serviced regularly by changing the external filter and flushing the trans which also flushes the internal filter?

If not then a complete trans service including the internal filter should be done. It also is the symptom of a sticking valve body.
Click to expand...

Yes it has been serviced, we didn't flush the trans, but fluid has been changed and new filter put on. It's going into our cousins shop so he can hook it up to a computer and control the valve bodys / look for bad wiring.
 
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