I searched the forum but didn't find anything so here goes. My 03 alli with 26K miles will occasionally give me a false neutral when shifting from park to either reverse or drive.


Today I pulled into a store and was parked uphill. Went to leave 10 mins later, shifted into drive but truck wanted to roll backward and I got no forward motion from the throttle. By the time I hit the brakes and checked the shift indicator the trans had engaged. 2 or 3 other times I have been getting ready to back out of my garage (which is almost perfectly flat) and have had the same thing happen in reverse.


Trans has had a new spin-on every 8-10K miles and I changed the ATF at 15K. Never towed over 7000 lbs and temps have never exceeded 175. No unusual slippage once you are moving.


My only guess is that I'm low on ATF, guess I will check it after the trans is not and see what I get. I made sure I was back up to the right level after changing the ATF, it's only recently though that this problem has surfaced.


I'm just afraid that next time it will not come back and I'll be stuck.


Your suggestions are welcome! Thanks.


Fred G

How long prior to your problem did you service the trans filter. I have a simular problem with engagement, but it may not be related to yours. I think mine may be leaking around the filter seal where the filter goes into case of trans

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<TD id=HB_Focus_Element vAlign=top width="100%" background="" height=250 UNABLE="off">i just had this problem with my truck it is a neutral switch of some sort on the tranny and it will do that. Take it into your dealer and they will fix it on warrenty</TD></TR>
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Fred


Good idea check fluid first ....


More then likely you may have a NSBU (neutral safety ) failure ....





Mac

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ya thats what i had wrong with mine was the nsbu switch


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Neutral/NSBU switch..thanks guys! Was hoping to not go to dealer and/or wait until they could replace those wacky tailgate cables but they said late summer on the cables, don't think I can wait that long!


Fred G

Is it easy to change these NSBU switches?

Neutral/NSBU switch..thanks guys! Was hoping to not go to dealer and/or wait until they could replace those wacky tailgate cables but they said late summer on the cables, don't think I can wait that long!


Fred G There is a good GMC dealer on the East end of 28th street.....waiting for your arrival with new NSBU in hand......

Is it easy to change these NSBU switches?


Isn't to bad at all ... Pushing it on the selector shaft and insuring it's properly aligned is about the worst of it ...


Mac