indicator light problems

[DADGLW]

couple days ago the indicator light didn't come on in neutral or reverse, now all that show are reverse ,3rd and 1st. seems to shift alright when in drive, but if you put it in 3rd it won't shift out unless you go to neutral then back to drive . No ses lig
ht shows. would that switch on the tranny be the problem? when you start it up 1st gear indicator lights up..any ideas?? this is on my 02

[jbplock]

Your symptoms do point to a faulty NSBU (Neutral Start Back-Up) switch. Here

[Nels]

I am glad to see this topic so well covered, as I am now having intermittent problems with my NSBU switch. I read Jim's article and searched the forums here, and found some good information. I am now wondering which replacement to buy. Of course, GM wants way too much $$. Having no Allison dealership nearby, I have been searching for other alternatives. I searched the Advance Auto web site and was linked to these two possibilities:

<http://www.partsamerica.com/ProductDetail.aspx?MfrCode=NIE&MfrPartNumber=NS37651&PartType=401&PTSet=A>
I hope that link works. If not, try this: http://tinyurl.com/2fngp3
At $37, this is the cheapest one I found. Manufactured by Neihoff.

They also offered this one:
<http://www.partsamerica.com/ProductDetail.aspx?MfrCode=SMP&MfrPartNumber=NS85&PartType=401&PTSet=A>
If the link breaks, try this one: http://tinyurl.com/2euh6f
This one is made by Standard Motor Products at a price of $51.

These appear to be the same switch made by different manufacturers. Does anyone have an opinion to offer as to whether one is better quality than the other? Is there any difference other than the manufacturer? I noticed the shipping weight on the Standard switch is double what the Neihoff switch is, if that is any clue. There is an Advance Auto store here in town, and I will stop by there today to see if they have these in stock. Hopefully they have both, so I can see & compare them. If not, I will order one of the units linked above.

Nels
Manitowoc WI
01 2500HD D/A

[DmaxMaverick]

Nels

www.gmdieseltech.com lists it for $70. About what you'd find at the Allison distributors. It's also at www.gmpartsdirect.com and www.rockauto.com for about $100, and the GM list is about $190.

I'm not sure the one listed at Advance AP (via your links) is the correct switch. Hard to tell, but it doesn't look right, and it seems too cheap. Many (if not most/all) of the parts stores can't/won't distinguish between the Allison and 4L80 (and others) switch. The switch listed at www.gmdieseltech.com is the genuine Allison part. After problems associated with the original (black) switch, I don't think I would try an aftermarket, even at 1/2 the price, if one is available.

[DADGLW]

i got mine at a AutoValue parts store..around $40...same as the one i took off.. compared it to the one at GM dealer, looked the same to me...at a lot less. guess time will tell.............

[Nels]

Well I'm going to find out, one way or another. I stopped at Advance Auto yesterday, and they cannot get a replacement for that switch. When I told them that the Advance Auto web site linked me to this one, they explained that they share a web site with Checker, and both link to the PartsAmerica site. I ordered the $37 Neihoff switch from PartsAmerica. If it isn't right, the page says I can return it to any Advance Auto store location for credit (wierd system). The only thing that concerns me is there was no way to tell if this is the upgraded switch with the seal for the shaft. I guess I'm not too worried about it because the original switch lasted 6 years and 93,000 miles without the seal. If I get similar service from the new one I will be happy. If not, it only takes a few minutes to change it again (having paid $37 for the education).

[Nels]

Update:
I ordered the $37 Neihoff switch from partsamerica.com on Friday morning and received it Monday afternoon. Not bad. This switch is the black case without the extra seal. :-( I installed it this morning. Easy job except for the stubborn plug connector (big one on top). Hopefully it will last as long as the original.

When I looked at the original switch I removed, I saw it was made by Lucas (Prince of darkness). ;-)