Duramax Diesels Forum Truck of the Week
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Old 07-25-2017, 01:29 PM
Gman327 Gman327 is offline
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Default Lb7 neutral drops

Trans or tc has been acting up for a while now, under heavy acceleration truck will go into neutral from the 2-3 shift and reengage once I let off the throttle. Only code I got for it was p0776 once, tc was out a few months ago looked good at the time tailshaft is tight now. Ordered new speed sensors waiting for them to come in now speedo was jumping around a bit last winter any chance this could be my problem, any advice is greatly appreciated.
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Old 07-25-2017, 01:55 PM
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Could also be a blown out C3 piston.
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Old 07-25-2017, 02:54 PM
Gman327 Gman327 is offline
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I hope not sounds like an overhaul if that's the case. Seems to do it with ease in 4wd also not sure but could be 2nd gear in 4hi and spin in loose will cause it. Did drain and filter 2k ago fluid looked fine and seems fine now going to drop the pan tomorrow and see if there's anything obvious to me. Any and all suggestions greatly appreciated.
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Old 07-25-2017, 03:08 PM
Gman327 Gman327 is offline
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Going to bypass the copilot also seems like the throttle position sensor on it could be acting up the lights on the copilot seem to be erratic, though the wire looks fine.
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Old 07-25-2017, 04:02 PM
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Did I hear copilot?


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Old 07-25-2017, 04:34 PM
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Is it an ATS trany with 5 Star ? and what did you look at when you pulled converter ? who knows what question might spark a fix to your problem .Good luck!
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Old 07-25-2017, 04:41 PM
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I bet the C3 clutches look like an accordian.
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Old 07-25-2017, 05:06 PM
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Nadp heavy hauler with co pilot
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Old 07-25-2017, 05:12 PM
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Funny thing is is shifts fine runs awesome till I lay on it hard down low and it lets go into neutral. But I have no clue about the Allison, cracked the rear case a few years ago only time I had it out
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Old 07-25-2017, 07:17 PM
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Quote:
Originally Posted by Gman327 View Post
Nadp heavy hauler with co pilot
You didn't get much of a trans.
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Old 07-25-2017, 07:24 PM
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Sad thing is it's the second one too from warranty added the deep pan and big cooler too
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Old 07-25-2017, 07:51 PM
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Default Lb7 neutral drops

Polishing a turd

How's the truck run? Sounds like a smoke machine. Ppe box and no maf?


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2003 CCSB LT LB7 deleted

Some cool stuff, some fast stuff, some slow stuff
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Last edited by Awenta; 07-25-2017 at 07:58 PM.
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Old 07-25-2017, 08:37 PM
Gman327 Gman327 is offline
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Yea it's a peice of shit forsure but my trans problem proceeds my compounds I don't know everything I'm here for help the truck isn't my dd and it runs mint maf code only gets thrown on ign cycles!
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Old 07-25-2017, 08:39 PM
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You have an Allison that neutral drops?! I want it!
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Old 07-25-2017, 09:11 PM
Gman327 Gman327 is offline
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Sold! Not nearly as cool as it sounds needs a tranny lol
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