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Discussion Starter · #1 ·
Hey guys, I have read all thru the forums about the neutral safety switch causing this problem but mine seems to be a bit different as it doesn't throw any codes....sort of.

First let me start with I bought this truck a month ago and don't know any history on it so I am changing all the fluids and filters so I have that on my records.

It has 217xxx on the clock. So I change the engine oil and filter, all good there (it did flash me low oil warning in the DIC as it was rebuilding pressure, is that normal?) Then I dropped the spin on Ally filter and notice no magnet. this was a sunday so I had to wait to get the part on monday. Looking back i wish I had put the filter back on to prevent anything weird from happening! HA!!

So a friend needs help moving and I think (just out the old filter back on for now, then drop the pan later and do the service). Start it up and it won't go in gears, I can move the lever and the indicator on the dash shows a light around all the different gear but no drive. After a few seconds in each gear the light surrounding the number/letter starts to blink.

I never saw any check engine light or message in the DIC but.....
A friend comes over with his code reader and there was a P0700 code and another (he cleared them before I could write them down....Grrrrr). I know the second code was in the Transmission section, but again not sure what it was. Satrt it back up hoping clearing the codes solves the problem (like it was the low pressure, loss of prime issue) but no luck.

Now it won't store any codes, it won't go in gear and to make matters worse it seems like every time I start it to try it out there are more and more strange noises coming from underneath, tonight I heard what sounded like a belt chirp but coming more from the bellhousing area and definitely crank shaft and RPM based in frequency.

So now I'm freakin out that I hurt this thing trying to do a simple fluid change.

Help please!!
 

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How much trans fluid is in it?
 

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Discussion Starter · #3 ·
I haven't been able to get it to operating temp to get the proper reading but the dipstick shows the leverl between the hot and cold ranges
 

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Discussion Starter · #4 ·
OK, update to where I'm at. I was able to get the NSBU switch from a local Allison dealer for less than 80 bucks. I put it on Monday afternoon and no change to the condition.

I am not surprise by that but it eliminates a variable. I was able to disconext the Trans connector on a suggestion from another thread and it does go into limp mode now. Shifts very hard into reverse and forward (3rd). Of course I got all kinds of warnings and a bunch of codes now about every solenoid and over temp etc.

Does this tell us anything? For me it eliminates the transmission pump losing prime as well since it goes in forward and reverse gears.
 

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Discussion Starter · #5 ·
Well I hope this helps someone else down the line. My trouble ended up being the internal filter was completely stopped up. The guy that worked on it for me is an Allison certified tech and he said if the external filter is off long enough when the pump re-primes the fluid path it will suck up the sediment in the pan clogging the screen. The Transmission then allows a small amount of fluid thru a bypass passage so "limp home" is still in play. New filter and fresh fluid and problem solved. Shifts like brand new now with 217XXX on the clock.
 

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Good deal
 

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Thanks for letting us know what the problem was, haven't heard of that one. Good to know.
 
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