# 4L80E won't move when cold



## 97135 (Feb 26, 2011)

Hi, new here - 1st question actually. 

We have a '06 GMC HD 1/2ton with 6L and 4L80E. When sitting outside in the cold, the tranny won't shift at all. Push truck inside for the night and we can drive it out the next day after cycling the shifter through all the gears. Sometimes a rattle sounds from torque converter area when idling and goes away when able to put in gear and move. Are these likely torque converter or pump or solenoid issues or may it be something totally outside of the transmission like electrical issues to start troubleshooting? Is there a common failure on these transmissions or is it more likely a complete rebuild is needed? Thanks for the help.


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## Ozark Hillbilly (Feb 10, 2011)

How many miles are on the tranny?


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## 97135 (Feb 26, 2011)

around 200,000 KMS


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## Ozark Hillbilly (Feb 10, 2011)

I'd recommend having a new filter installed on the pickup in the pan and replacing the transmission fluid at a shop that has a transmission fluid exchanger. They can do a more complete fluid exchange that way. What you have described could be due to low flow from the pump which sometimes will be corrected by the new fluid and filter. Could also be a solenoid problem. Fresh tranny fluid has a strong solvent action and will sometimes help unstick things as it gets pumped through the transmission as you drive.

You should also have the codes scanned. Not all codes will turn the light on.

If there are no codes and the fluid/filter exchange does not help after it is driven 40 km or so then it would be time to start asking yourself some basic questions about the truck. Since it has 200k kilometers if you plan to keep the truck for a while still and will be willing to also do the other repairs that will probably come up during that time then it may well be better in the long run to go ahead and swap the transmission instead of even bothering to diagnose and repair the specific problem with the tranny. Done that way you can have more confidence instead of waiting for the next weakest link to fail in the transmission after the first repair.


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## 97135 (Feb 26, 2011)

Thanks for the help. I'll check into these and see what happens. I may have found a used one if I need to go that route. Yes, I do plan on keeping the truck for quite a while yet but I do hope to not have to spend a fortune for this repair.


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## mcwlandscaping (Sep 8, 2005)

Ozark Hillbilly;1254792 said:


> I'd recommend having a new filter installed on the pickup in the pan and replacing the transmission fluid at a shop that has a transmission fluid exchanger. They can do a more complete fluid exchange that way. .


I'm not sure but doesn't GM spec NOT to do a power-flush on those transmissions?? I could be mistaken but that can cause a lot of harm if its done to a trans it shouldn't be done to!


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## KatWalk (Oct 12, 2002)

I'm not sure if GM recommends not to do it but this is why I am here looking to see if anyone had suggestions. I have a 06 2500hd with 73k that I would consider to be "worked" miles. Decided to have tranny flushed along with front/rear diff and transfer case. Two weeks later, the tranny started to "pop" through the gears versus shift normally and smoothly through. Brought it back to the shop and they drove it and put the scan tool on it and said that the code said there was a slip between 3rd and 4th followed by blah blah blah B.S. We ended up dropping the pan and changing the filter and topping off the tranny fluid. Driving around town normally there seems to be no problem. Drive ten miles up the high way at 70-75 mph and come off the exit and tranny starts to shift hard again. Let it sit for an hour, no hard shifting. Tranny is running around 140 degrees. At this point I am so upset, I have almost been considering going to a local Valvoline instant oil and having them do a new flush. They did not do the first flush. I am all over the road but don't think this tranny is junk.


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## BlizzardBeater (Aug 29, 2010)

97135;1255735 said:


> Thanks for the help. I'll check into these and see what happens. I may have found a used one if I need to go that route. Yes, I do plan on keeping the truck for quite a while yet but I do hope to not have to spend a fortune for this repair.


In the long run, a used transmission will cost you more money, I promise. If you do end up swapping transmissions, spend the smart money on a GM factory remanufactured transmission. Unbeatable warrunty and fully tested. Just think, that used transmission is there for a reason. Almost every junkyard will tell you it was a wrecked truck or only has 30,000 miles, but can they prove it? If you're going to take the time and spend the money, do it once. Just my opinion.


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## mcwlandscaping (Sep 8, 2005)

BlizzardBeater;1275161 said:


> In the long run, a used transmission will cost you more money, I promise. If you do end up swapping transmissions, spend the smart money on a GM factory remanufactured transmission. Unbeatable warrunty and fully tested. Just think, that used transmission is there for a reason. Almost every junkyard will tell you it was a wrecked truck or only has 30,000 miles, but can they prove it? If you're going to take the time and spend the money, do it once. Just my opinion.


Absolutely!!!!!!!!


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