Duramax Diesels Forum Truck of the Week
Old 10-09-2011, 11:40 AM
Tank01 Tank01 is offline
Join Date: Dec 2010
Posts: 31

Default LB7 Hard Shift Cold

Not a Diesel Tech,,,,, Transmission and TC rebuilt Jan 2001, rebuilder was recommended by a friend (I think he is in jail now, unable to locate). Issues after rebuild, (I learn hard I know). I took my truck to Texas Performance Diesel in Emory TX, (great people) they worked on Electronic Issues and corrected, since then all has been fine until recently.

As the weather cools, truck shifting hard when cold. First thing on start up it does not want to "engage" when shifted to drive, first dozen or so shifts very hard and some what funky. After a very short time runs and shifts as smooth as ever. I've removed the programer and this does not seem to make a difference. Changed the external filter and running fresh Transynd flulid.

I feel this is something that could be electronic in nature, any idea?
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Old 10-09-2011, 07:37 PM
chaser's Avatar
chaser chaser is offline
Join Date: May 2011
Location: dallas, texas
Posts: 16


mine did the same thing last winter along with slipping into neutral out of first, then slam into 2nd and get stuck there. it would eventually go into limp mode and throw the check engine light. didn't have a way of getting the codes off the TCM but after shutting the truck off and letting it sit for a few then starting it back up it would shift fine. then after the next key cycle the light turned off. problem would start all over with the truck sitting over night.

not a tech either but I was thinking it is a solenoid in the valve body. waiting to see if it does it again this year so I can track it down but hopefully someone will post up..
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