Lbz trans help

kmb06

kmb06

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Jan 8, 2014
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Hello everyone having some issues with my 2006 GMC Sierra LBZ. Some history on the truck and issues, truck has 300K on the clock and is basically stock besides EFI live with Idaho Rob Tunes. Transmission had an overheating issue around 230,000 and with the help from this page I come to the conclusion that the torque converter was burnt up so I replaced it and that solved my issue. About 10000 miles ago the truck started going into limp mode and from the codes I replace the valve shift spring and installed a transgo Jr at the same time. And now whenever the transmission reaches over a hundred and fifty degrees it will go into limp mode and stick in 4th gear, at some point in time it will also stay in 3rd gear but when you shut the truck off and restarted it will be in 4th since this issue has started within the last few days truck has also stuck in first gear a handful of times. But it is only whenever the trans temp gauge goes over a hundred fifty degrees. It's been really hot outside the last couple weeks but usually the transmission never goes over a hundred and fifty degrees unless you're in traffic or something. Codes that came up this time are p0700 p0776 p0777 p0742.

Anybody that can shed some light on this and help me get through this issue that would be greatly appreciated thanks in advance.
 
kmb06

kmb06

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Jan 8, 2014
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Call me crazy but wiggle the big plug on the back of the transmission on the passenger side and restart the truck it will actually do just fine until next time you shut it off:mad:
 
clrussell

clrussell

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Sep 23, 2013
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kmb06 said:
Call me crazy but wiggle the big plug on the back of the transmission on the passenger side and restart the truck it will actually do just fine until next time you shut it off:mad:
Click to expand...

Any fluid in that plug?
 
C

Cougar281

Well-known member
Sep 11, 2006
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St Louis, MO
clrussell said:
A lot of random shit..
Click to expand...
Why? ATF is non-conductive.... If ATF in the main plug will cause issues, you can bet all the parts (solenoids, PSM, IMS) will go haywire being submerged in it and all ;). Now if it's WATER, that's a different topic.

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clrussell

clrussell

pro-procrastinator
Sep 23, 2013
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Cougar281 said:
Why? ATF is non-conductive.... If ATF in the main plug will cause issues, you can bet all the parts (solenoids, PSM, IMS) will go haywire being submerged in it and all ;). Now if it's WATER, that's a different topic.

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Click to expand...



I don't know why but I've had trucks leaking fluid through the plug and it causing weird codes. One would limp very consistently, cleaned the plug in with brake clean and compressed air dried it, put die electric silicone in and fixed it.. Been problem free for 3 months now. He knows it needs an internal harness to fix the leak but is to cheap


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G

gassux

Member
Mar 14, 2010
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that harness is a PITA to replace but i'd give it a try. You would be getting about 10 codes from the control valve(valve body) if the harness was bad though. I think you can get the harness for 130.00 online, just make sure you push it all the way in to the connector. It's a pita connection, I used toothpicks to hold the bottom tabs and was able to push the top tabs w/ my fingers. good luck
 
kmb06

kmb06

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Jan 8, 2014
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Actually it does seem to see if a little fluid from that plug I just never thought twice about it, thought maybe one of the pins in the plug in or something they have been bad.
 
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