1996 K1500 shifting problems

hunterflinner · May 25, 2015

I have a 1996 chevy k1500 with a 4l60e transmission. I recently put a brand new 4l60e in this truck. I took it for a test drive and it seemed to slip shifting into 3rd gear, then it seemed to have problems shifting into overdrive. It seems to get stuck in between gears for a little bit when it shifts into overdrive. I have read that it could be a throttle postioning sensor so I replaced it and it still does it. I also replaced the neutral safety switch as well. I'm a little frustrated since this is a brand new tranny and it still is acting up. Any help?

gmtech4 · May 25, 2015

Warranty , failed upon install , go get another one UNDER WARRANTY !!!

Doug_Scott · May 25, 2015

+1

Does the company that you purchased this transmission from also cover the labour to replace a defective product, or at least offer to do the labour for you?

What was wrong with original transmission? Hopefully not the same issues.

gmtech4 · May 26, 2015

+1

Does the company that you purchased this transmission from also cover the labour to replace a defective product, or at least offer to do the labour for you?

What was wrong with original transmission? Hopefully not the same issues.

No to the labour I'm afraid , only the product they sold

hunterflinner · May 26, 2015

The old tranny was doing the same thing. I am wondering if its some kind of sensor or the computer acting up.

gmtech4 · May 27, 2015

The old tranny was doing the same thing. I am wondering if its some kind of sensor or the computer acting up.

Holy shit , the tranny comes with new stuff soooooo I'd just take to a shop , you've hemoraged enough cash ., better yet , sell it

hunterflinner · May 27, 2015

Could it be the computer messing up? I bought this truck as a project. It originally had a 305(5.0L) in it and I put a 350(5.7L) in it. I used the same equipment off the old engine such as sensors, intake, fuel injectors, throttle body, ect. This is when the original transmission started acting up. I thought it was just going out so I kept driving the truck until the transmission was slipping so bad I couldn't drive it. I had a friend who is a gm technician rebuild another tranny I picked up cheap. He put upgraded parts in it to make it a little more heavy duty as well as a transgo shift kit for smoother shifting. I stand behind his work because he is so particular about everything that he does. He spent a great amount of time on this transmission making sure it was put together correctly.(this is not his first 4l60e rebuild and upgrade) It's just funny I put the transmission in and drove it down the road and it is doing what the original transmission did before it fully went out. Thanks for the help.

Doug_Scott · May 27, 2015

Personally I have no experience with GM transmissions or how they are controlled. I think that my 2010 GMC has a 4L60E transmission and it has its own "computer"(TCM). All shifting functions can be tuned via that TCM. No idea when they started that, or how it was implemented originally. I know my 2000 GTP also had a similar trans (it was transverse though) and appeared to me to have its own computer as well. There was a performance shift button that did similar things that the tow/haul button does.

Does your truck have a tow/haul button? Have you tried it to see what difference it makes?

One thing for sure, stop driving it until you figure out what is causing it. Does your buddy not have troubleshooting experience with this transmission? Sometimes the best thing is to recognize when you are in over your head and get a professional to look at it. I have shitloads of experience on pre-computer torqueflytes, and wouldn't even attempt any diagnosing beyond fluid levels and connections on the trans in my truck. It just plain costs too much to guess these days.

gmtech4 · May 28, 2015

Personally I have no experience with GM transmissions or how they are controlled. I think that my 2010 GMC has a 4L60E transmission and it has its own "computer"(TCM). All shifting functions can be tuned via that TCM. No idea when they started that, or how it was implemented originally. I know my 2000 GTP also had a similar trans (it was transverse though) and appeared to me to have its own computer as well. There was a performance shift button that did similar things that the tow/haul button does.

Does your truck have a tow/haul button? Have you tried it to see what difference it makes?

One thing for sure, stop driving it until you figure out what is causing it. Does your buddy not have troubleshooting experience with this transmission? Sometimes the best thing is to recognize when you are in over your head and get a professional to look at it. I have shitloads of experience on pre-computer torqueflytes, and wouldn't even attempt any diagnosing beyond fluid levels and connections on the trans in my truck. It just plain costs too much to guess these days.

Your GTP did not have its own TCM , the PCM took care of everything , I'm not sure if your 2010 has a TCM , I doubt it lol

Could it be the computer messing up? I bought this truck as a project. It originally had a 305(5.0L) in it and I put a 350(5.7L) in it. I used the same equipment off the old engine such as sensors, intake, fuel injectors, throttle body, ect. This is when the original transmission started acting up. I thought it was just going out so I kept driving the truck until the transmission was slipping so bad I couldn't drive it. I had a friend who is a gm technician rebuild another tranny I picked up cheap. He put upgraded parts in it to make it a little more heavy duty as well as a transgo shift kit for smoother shifting. I stand behind his work because he is so particular about everything that he does. He spent a great amount of time on this transmission making sure it was put together correctly.(this is not his first 4l60e rebuild and upgrade) It's just funny I put the transmission in and drove it down the road and it is doing what the original transmission did before it fully went out. Thanks for the help.

What Doug said ,,, have your buddy road test it , 19 yrs old and played with , mmmmmm still advising selling it and get something newer

Doug_Scott · May 28, 2015

Your GTP did not have its own TCM , the PCM took care of everything , I'm not sure if your 2010 has a TCM , I doubt it lol

My truck does have a TCM. It mounts next to the PCM. I know this because I have the original one still stock(along with a stock PCM), and another one modified and plugged in. The 6 speed has it built into the transmission.

hunterflinner · May 28, 2015

My buddy now knows about it and he is going to try and troubleshoot it. I know he will make it right, I just thought I would come on here and see if anybody might know what was wrong with it before I bugged him. Thanks again.