PRND Indication trouble

[Masbro]

I have a 2001 Duramax chev 3500 and recently I have indicator problems
after driving for 1/2 hour or more the N D only,indicators on display do not light up?
There are no trouble codes, transmission shifts and works ok then after sitting for a while it will work again and do the same.
When it quits indicating I can move the shift lever from park to 1st it will indicate in all positions momentarily on display

Any help of where to start would be greatly appreciated
Thank you
Masbro

 

[LBZrcks]

:hello::welcome2:

Might get some more help here

 

[malibu795]

NBUS nuetral back up saftey switch...

bet your door lock dont unlock either when put in park after they were locked while in R or D

 

[Masbro]

Prnd

NBUS nuetral back up saftey switch...

bet your door lock dont unlock either when put in park after they were locked while in R or D

Where is it? And, Yes the door lock unlocks works in PRD when indicator does not indicate or indicates
the the PND are the only ones that go off after trans gets warm then it will work again when sitting overnight ?
Why is that? Strange That it happend's this way mabe it is the TCM module what do you think?

Any Help
thanks

 

[Masbro]

:hello::welcome2:

Might get some more help here

I hope so

 

[Masbro]

Help

Not getting much help here ??
WILL try to find another site
Thanks anyway

 

[beach_33]

nsbu is on the driver side of the truck mounted on the side of the tranny. probably a little tan box with two plugs going in to it. two bolts hold it to the case. one bolt holds the shift linkage. you wont find a better site for info i can promise you that

 

[Masbro]

nsbu is on the driver side of the truck mounted on the side of the tranny. probably a little tan box with two plugs going in to it. two bolts hold it to the case. one bolt holds the shift linkage. you wont find a better site for info i can promise you that

That may be so about help!
But my problems dont have the symptoms described above, why does this only happen when engine runs for about half hour or so and then is ok next day and then dito??

 

[beach_33]

are yo sure there arent any codes. could be a problem with the actuall shifter. maybe a bad ignition. i would try the nsbu first. it can do wierd things to a tranny and it is cheap. 50 dollars from allison dealer

 

[Masbro]

are yo sure there arent any codes. could be a problem with the actuall shifter. maybe a bad ignition. i would try the nsbu first. it can do wierd things to a tranny and it is cheap. 50 dollars from allison dealer

Thank you for the reply!
Yes I am sure there are no codes. I even invested in a Innova 3140 (Equus) ScanTool, Checked ignition,the shifter has no linkage to trans.
all electronics it also only happens when I drive or run engine after half hour or so. I was told by a chev mech that he would change out the TCM.Module
about 170.00 at auto supply store?
I guess when It gets a little warmer here in wisconsin I will check all electronics, I am a retiered IBEW Journeyman electrician and have 30 plus
years experiance in elecronics should not be too bad: have plenty of the best Fluke meters and tools to tackle this
I guess this problem is something that no one encountered here ?
Thought it would be easy, well nothing is easy with my Duramax! At 60,000,
and going to the dealer I know I would get raped, ex. 130.00 for them to change out a winshield washer pump on my wife's Blazer, cost me 15.00
plus 40min labor and 2 beers hehe
Thanks for help

 

[beach_33]

while this tranny is mostly electronic it most certainly has a shift linkage. it is on the driver side of the tranny going in to the tranny. i would for sure change the nsbu . its what the shift linkage goes into. since you live wisconsin where i am sure there is snow and road salt this could verywell be your problem. plus its only 50 bucks from alliso dealer

 

[Masbro]

while this tranny is mostly electronic it most certainly has a shift linkage. it is on the driver side of the tranny going in to the tranny. i would for sure change the nsbu . its what the shift linkage goes into. since you live wisconsin where i am sure there is snow and road salt this could verywell be your problem. plus its only 50 bucks from alliso dealer

Hi
Thanks for that, I will do that!
Another strange thing happened today I GOT A FAULT CODE wow.
It is P0700 which is the TCM module. But as I see it you are VERY knowledge
on this and it may not be that the fault code, I had to reset it Engine ran like sh_ _.
Thanks for the help; I will change out the nsbu. Like you said on driver side of tranny


Fred

 

[radvans]

Losing the indicators is a standard sign that the nsbu is going out. Even in sunny socal I have replaced two. It happens at different times and there are a few different signs that point to the nsbu. The dissappearing indicator is a big one. Eventually you will not be able to shift in to all the gears.

The last time mine went bad I was moving my trailer and backing/going forward a few times. It still drove but the indicator was gone and then it started having shift problems and felt like the brakes were one. Mike L. (on this site and the best allison guy in the country) gave me a quick 411.

Its easy to replace you can do it in 15 minutes. If you have specific questions give him a call he is always happy to help anyone and he lists his numbers in his sig for all to see. Just do a quick search for it.

Good luck.

 

[radvans]

Saw him in another post.

Mike L. Englewood Transmissions

Shop 714 870 7300
Cell 310 918 9678

 

[Cougar281]

Sounds a lot like the NSBU. The older ones where known for going bad. FWIW, your Equus scanner won't pull codes from the TCM; I don't think there are any consumer (such as available at Wal-Mark, RicerZone or similar) scan tools that will. If you have an Allison dealer near you, you could probably get a NSBU there much cheaper than a GM dealer.

 

[Masbro]

Saw him in another post.

Mike L. Englewood Transmissions

Shop 714 870 7300
Cell 310 918 9678

Hi
Well thanks for that I will get one in the morning, and replace.
And I also have problems some times it going into drive unless I turn off engine and try again
Thanks again

 

[Masbro]

Sounds a lot like the NSBU. The older ones where known for going bad. FWIW, your Equus scanner won't pull codes from the TCM; I don't think there are any consumer (such as available at Wal-Mark, RicerZone or similar) scan tools that will. If you have an Allison dealer near you, you could probably get a NSBU there much cheaper than a GM dealer.

Hi

Live in a small place like 60000 La Crosse WI. will have to get it from my local auto parts they can get alison parts yes you are right Dealer would rape charge me.
sure nice to get this GREAT help here!

Thanks

 

[Masbro]

NSBU switch

are yo sure there arent any codes. could be a problem with the actuall shifter. maybe a bad ignition. i would try the nsbu first. it can do wierd things to a tranny and it is cheap. 50 dollars from allison dealer

You guys vere right it was the switch and or the plug had to go to dealer
could not get part here very pricey simple switch. had to pay
220.00 NSBU
122.00 plug WOW unbelieable prices GM gets
Plug was so corroded it broke the contacts when it was removed.
My tranny problem got to the point where it woul not shift in any gear or indicate I took the switch appart after drilling out many rivets found it
electricaly not too bad so it was combination of plug and switch glad it it
was not the module etc.
also thanks Malibu795 for your help
Dealer gave me a break took off 25% so I guess 507.00 was better than full price
Thanks for you help here

 

[beach_33]

glad yo got it figured out