I am trying to help my dad with a problem on his 02 duramax-allison crew cab short bed. On numerous occasions while pulling into his driveway(steep driveway, sharp right turn up hill, with cab over camper) transmission acts like it goes into nuetral and then all of the sudden engages with a bang. The only time this has happened is when turning into his driveway. Yesterday this happened and it set 3 codes, PO 700, PO 843, PO 875. Does anyone have any experience with this type of problem? Could there be a wiring loom problem that is only experienced when the frame twists? He is having a hard time finding a dealership in N. Calif. that has any decent duramax-allison techs and I haven't been able to contact a good friend in his area that is a good tech. His truck has about 38,000 miles on it. Any thoughts would be greatly appreciated. Does this sound like a symptom for NSBU switch? Does anyone have a list of items covered by emmisions warranty? Seems like a lot of the dealers are not letting their customers know that some of these parts are covered and just charging them. Thanks for your help in advance. P.S. I read through the code description on my all data link so I am not totally in the dark.:help:

How is the fluid level? It sounds like it could be getting a gulp of air if it only happens on the steep driveway.

Thanks, I will have him check it. The tranny was just serviced at local dealership.:confused:

Checked fluid level and it is OK. Codes again are PO700, PO843,PO875. Truck has only acted up about 4 times and every time was after about 70 miles of driving and when pulling into uphill driveway during right turn, feels like false nuetral. NSBU? 2002 truck.:confused:

I hate to be so dumb, but what is a "NSBU"?

Nuetral Safety Back Up