Hello tranny guru's. My girlfriend's dad has a '04 LLY dmax/allison 2500 cc 4x4. He owns a boat/r.v. dealership and prob. tows as much as he drives unhooked with it, mostly interstate. He has 67k miles on it and has never chaged the original fluid or filter on the tranny- I know not good! He has the SES light on and we ran the codes at the local auto zone and come up with P0700 and P0872. From research on here I know the NBSO Switch is pretyy common but he does not have any mods to the truck at all - not even a drop in k&n. I don't know what to check next or what part to try that would most likely fix it. If anyone has expierenced this or knows what to do next please let me know. I have ordered a edge with ***. and airraid intake and 4" exhaust for it but we don't want to put it all in yet just in case it's something we can get the dealer to cover under the warranty. Thanks for this great site with tons of helpfull info. Natehttp://www.dieselplace.com/forum/images/smilies/rockon.gif
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Are there any symptoms other than the SES light? Hard 2-1 shifts? Feel like it is in neutral at a stop light? Erratic shifting?
From the meaning of the DTCs:
P0700 the TCM turned on the light for some reason.
P0872 Short in 4th Clutch Transmission Fluid Pressure Switch Circuit, or 4th Clutch Transmission Fluid Pressure Switch Stuck ON.
It looks like the pressure switch needs replacing.

My experiances with p0872 have mostly led to a sticking shift valve in the valve body.