NSBU Symptoms

[BudTX]

We have had bitterly cold weather here lately, with more on the way, and
I think that my NSBU switch is crapping out.

The bar underlining the gear disappears on the DIC, and the truck will rev but will hardly move when trying to back out of the garage. I get the Shift Range Inhibited message as well. I had to drop in down to 1st to get it to drive forward so that I could re-park it.

I understand that there exist more than 1 version of the NSBU switch. I am not close to my truck right now, and did not crawl under it to look and see which one I have. What are the differences between the two? My truck is a 2004.5 LLY.

Thanks,

Bud

 

[RENODMAX]

That's what my nsbu did when it crapped out. The two different versions were the old one which was not waterproof and the new one which was. That's how I understood it anyway. One is black and ones brown forget which is which but I'd get a new Allison unit. That's what I did and no problems since

 

[stroke250]

your lly should only have one style of nsbu and its the single connector one.

 

[BudTX]

I just got home to check, and it is the single connector.

R/R seems pretty straightforward, i.e. 2 bolts and an electrical connection,working around the front drive shaft.

Any pointers from those who have done it?

 

[BudTX]

I found some helpful advice from an Allison dealer in the area called Midwest Bus Service in Bonner Springs, KS. They specialize in buses, but their head mechanic walked me through the install when I went to the shop to pick up the part (at a price that beat the heck out of any other vendor, I might ad). He also loaned me a tool that will help ensure that I keep the NSBU switch in the neutral position when I install it tomorrow.

Great guys all around.

 

[TIM Z]

Hope it works out for ya Bud.

 

[RENODMAX]

I just got home to check, and it is the single connector.

R/R seems pretty straightforward, i.e. 2 bolts and an electrical connection,working around the front drive shaft.

Any pointers from those who have done it?

Just unbolt and plug in. Make sure you dont move anything while its unplugged and youll be fine.

 

[stroke250]

also a good idea to deburr the shaft before installing the new one as the nut tends to mushroom it out when tightened. this will allow the new one the slide right on.

 

[05smoker]

Same thing happened to one of our shop trucks. He said it was stuck in 3rd and the P0733 code would not clear and the dash was not working properly. Called the local trans place and they said it was internal and would be $3500.:rofl: I told him to go and get an NSBU switch and swap it and that fixed it. Pretty said when the company treasurer is back in the shop telling them how to fix trucks.

LB7 has two connectors and LLY has one.

 

[JMK777]

bump.

I just picked up a 02 with my brother yesterday and I'm positive that the nsbu is shot. I get the disappearing indicator light, the 4x4 button wont go into 4h or 4l But the truck wont move at all when in any gear. dost the truck not moving part sound like a nsbu related issue as well? i'm also getting p0842 and p0700 and u1000. It came with those codes so I cleared them and charged the batteries which where dead and nothing came back. the p0842(A circuit low) code I'm not sure about.

 

[roxyfever]

I know this is old but will a bad switch cause the doors to lock and unlock randomly?

 

[gassux]

Are you getting "range shift inhibited" on the dash?

 

[roxyfever]

Yes

 

[mac2881994]

It may be possible for it to cause the doors to lock and unlock. If you have the doors set to lock when put into gear then a wonky NSBU switch may be sending erratic gear position info.

 

[Mike L.]

It may be possible for it to cause the doors to lock and unlock. If you have the doors set to lock when put into gear then a wonky NSBU switch may be sending erratic gear position info.

At this point you will have a P0708 code.

 

[roxyfever]

Thanks. Its my dads truck. It has some symptoms of the nsbu but it shifts fine and i dont believe he has any codes. So im trying to help him out

 

[09dually]

Wife got shift inhibited message today. Turned truck off, lock/unlock with fob restarted and was able to drive home. Did the same thing to me but couldn't get it to clear. Let it sit for couple of hrs and goes into gear now.

RPMs fluctuate slightly at idle in park which it never did before and wife said it shifted hard on way home. Does this sound like the nbsu switch?

I called local Allison distributor and they couldn't find my trans in the data base. Is the serial number on a small white rectangle with a bar code on passenger side? Also has a a date which I figure is mfg date?

 

[Mike L.]

Need info on truck and codes. Does not sound like NSBU.

 

[09dually]

Sorry, 2009 cclb drw lmm. No engine light, no codes came up with my scanner. just dropped it off at trans shop to have scanned. Might not get to it til tomorrow.

 

[09dually]

Should add that I was able to drive it just fine about 10 miles to shop. Seemed to shift fine other than going into reverse.