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Old 12-26-2011, 12:47 PM   #1 (permalink)
EDS_5_OH
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P0841, P0843, P0846 when tranny is cold and sits for more than 2 hours

All,

Did some searching, found some ideas, not sure what to try next. I replaced the NSBU switch last year when I was having Shift Range Inhibited in the mornings when it was below freezing. Seemed to fix the issue. Starting having the codes set (P0841, P0843, P0846) a few weeks ago when the temp is below 20 deg F and the truck sits for more than a couple hours. I replaced the ignition switch last week hoping this would solve the issue. It did not.

I have an ATS Deep pan and ATS stage 2 tranny with about 75k miles on it. The tranny has been flawless aside from this issue.

What should I try next? Could this be the deep pan filter has fallen down? Do I need to replace the Pressure Switch on one of the solenoids? Could the NSBU be bad again?

Any advice is appreciated,
Ed
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Old 12-26-2011, 01:58 PM   #2 (permalink)
Tanc Crusher
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Have you inspected all wire harnesses around the Allison for rub through as well as the plug in connectors?
Next maybe a co-pilot issue but no sure. They do weird things when they start to go bad.

Brian
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Old 12-26-2011, 03:25 PM   #3 (permalink)
EDS_5_OH
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Just inspected every wire harness I could find coming to and from the transmission. Everything looks good to me, all of them are secured in what looks like a factory location and none of the wire loom covers look worn at all. All the connectors look tight and pretty clean.

Would disconnecting the co-pilot and driving without it for a while be worth trying?
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2005 GMC SIERRA SLE
4X4 LLY DURAMAX
CC/SB

Nictane Filter, Dual Kennedy Lft Pumps,EGR Blocked, MBRP Downpipe Back 4", N-FAB Full Length Bars, EFI LIVE, Boost and Pyro Gauges in Trippin Gauge Mount
LBZ Intake
ATS Stage 2 With Co-Pilot

Bilstein 5100's, Congnito UCA's, Green Keys, Congito HD Tie Rods, Steering Braces, and Sulastic Shackles, 1.5" Blocks

Chrome H2's with Nitto Grappler 295/70/17's

Pioneer AVH-3400BH Stereo with Back-up Camera
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Old 12-26-2011, 04:25 PM   #4 (permalink)
Tanc Crusher
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Don't know anything about the co-pilot. Just what post and the sticky post about it in the Allison sections here.

Brian
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2007.5 GMT-900 Chevrolet Silverado 2500HD CC/LB LTZ 4x4 Summit White. 4-18-2007. Powered by the LMM Duramax 365hp/660tq coupled to the MW7 Allison 1000 6-speed through the NP1 NP263XHD Transfercase.
Upgrades: Performance Truck Products for 5" MBRP Turboback 6020AL. Alligator Performance for EGR Blocker. DuramaxTuner for EFI-Live with DSP5 ECM Tune and TCM tune. Meyer Performance for Airdog 150 Gen 1 Lift Pump, Diamond Down Pipe. Merchant Automotive for Suncoast IV with 1056 converter, Amsoil Synthetic Fluid in everything, Pitman Arm Fix.
Configure your FlashScan V2 the way it should be http://www.dieselplace.com/forum/sho...d.php?t=401770
Future: SDP S475 Twin Setup is here-install 6-18-11. On board Air with Side Step Tube Air Tanks, Custom Bed Fuel Tank and Water/Meth Tank.
New Toy: 2012 Dodge Challenger SRT8 Red and all stock for now.

Check out: My Garage for pics of the Truck, Mods, and Toys.
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Old 12-28-2011, 12:09 PM   #5 (permalink)
EDS_5_OH
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Any other ideas on what I should look at next? I disconnected the co-pilot and it made no difference this morning, same issue.
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2005 GMC SIERRA SLE
4X4 LLY DURAMAX
CC/SB

Nictane Filter, Dual Kennedy Lft Pumps,EGR Blocked, MBRP Downpipe Back 4", N-FAB Full Length Bars, EFI LIVE, Boost and Pyro Gauges in Trippin Gauge Mount
LBZ Intake
ATS Stage 2 With Co-Pilot

Bilstein 5100's, Congnito UCA's, Green Keys, Congito HD Tie Rods, Steering Braces, and Sulastic Shackles, 1.5" Blocks

Chrome H2's with Nitto Grappler 295/70/17's

Pioneer AVH-3400BH Stereo with Back-up Camera
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Old 12-28-2011, 03:10 PM   #6 (permalink)
Mike L.
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I would replace internal harness and pressure switch manifold.
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Old 12-28-2011, 03:29 PM   #7 (permalink)
Crafty1
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These codes indicate that you're having pressure dropping out. The P0841 and P0843 are C shift valve dropouts and P0846 is D valve dropout.

Because it is setting when temps are colder, make sure that you have good fluid level. Check it in Park with the engine running and trans warmed up. Ignore the cold band. It must be at least at the bottom of the HOT band with the trans temp at 160F.
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Old 12-28-2011, 08:09 PM   #8 (permalink)
EDS_5_OH
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Quote:
Originally Posted by Crafty1 View Post
These codes indicate that you're having pressure dropping out. The P0841 and P0843 are C shift valve dropouts and P0846 is D valve dropout.

Because it is setting when temps are colder, make sure that you have good fluid level. Check it in Park with the engine running and trans warmed up. Ignore the cold band. It must be at least at the bottom of the HOT band with the trans temp at 160F.
I'll check the fluid level tomorrow and make sure it's in the HOT band. After that, looks like I need to look at how change the internal harness and pressure switch manifold per Mike L's recommendation.

How expensive are these parts Mike?

Thanks for the suggestions,
Ed
__________________
2005 GMC SIERRA SLE
4X4 LLY DURAMAX
CC/SB

Nictane Filter, Dual Kennedy Lft Pumps,EGR Blocked, MBRP Downpipe Back 4", N-FAB Full Length Bars, EFI LIVE, Boost and Pyro Gauges in Trippin Gauge Mount
LBZ Intake
ATS Stage 2 With Co-Pilot

Bilstein 5100's, Congnito UCA's, Green Keys, Congito HD Tie Rods, Steering Braces, and Sulastic Shackles, 1.5" Blocks

Chrome H2's with Nitto Grappler 295/70/17's

Pioneer AVH-3400BH Stereo with Back-up Camera
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Old 12-28-2011, 10:25 PM   #9 (permalink)
Mike L.
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Quote:
Originally Posted by EDS_5_OH View Post
I'll check the fluid level tomorrow and make sure it's in the HOT band. After that, looks like I need to look at how change the internal harness and pressure switch manifold per Mike L's recommendation.

How expensive are these parts Mike?

Thanks for the suggestions,
Ed
About 100.00 for both.
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Old 01-03-2012, 02:49 PM   #10 (permalink)
EDS_5_OH
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Checked the fluid level and it was about 1/4 of a quart low. Filled it up to the middle of the HOT zone on the dipstick and it's been two days without the issue. Of course, it's been a lot warmer here for those two days also so I haven't seen temps below 20 deg. I'll keep everyone posted.

If the issue comes back, where's the best place to buy a manual that shows me how to replace the pressure switch and internal harness? Also, where would I order these parts from?

Thanks,
Ed
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2005 GMC SIERRA SLE
4X4 LLY DURAMAX
CC/SB

Nictane Filter, Dual Kennedy Lft Pumps,EGR Blocked, MBRP Downpipe Back 4", N-FAB Full Length Bars, EFI LIVE, Boost and Pyro Gauges in Trippin Gauge Mount
LBZ Intake
ATS Stage 2 With Co-Pilot

Bilstein 5100's, Congnito UCA's, Green Keys, Congito HD Tie Rods, Steering Braces, and Sulastic Shackles, 1.5" Blocks

Chrome H2's with Nitto Grappler 295/70/17's

Pioneer AVH-3400BH Stereo with Back-up Camera
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