1996 4l60e Shifting Issues

[kylespw80]

I happened across this forum and it looks like alot of helpful info! I have a 1996 chevy full size 1/2 ton 4x4 z-71. It has the 350 and 4l60e transmission. I bought it with a bad tranny and replaced it with a rebuilt unit. After putting it in and road testing it, it doesnt seem to wanna shift right. If you take it easy, it seems to go thru all the gears normally. But, if you put it under more of a load, it revs and kinda slides into the next gear and slips. It seems to do this thru all the gears. I contacted the transmission builder and he told me that I most likely have a wiring problem or a bad throttle position sensor. He also told me I may have a bad ground. Can anyone point me in the right direction? Thanks for all your help

[green 788]

It's a 4x4, so the speedometer sensor is on the transfer case, I believe (that's where it is on my 3500)...

 

I do know that if you unplug the speed sensor, the transmission will go into a default shift setting. Not sure how the 4L60 differs here from the 4L80 in my ton truck... but that might be a place to start...

 

...in other words, if you find that the transmission shifts okay with the speed sensor unplugged (but usually it will shift harder than normal--it will not slip, however)... then you have reason to suspect a data input issue, either from the speed sensor, possibly a throttle position sensor (especially since it seems to do okay when you're not accelerating hard)... or some other electronic device.

 

I talked to a transmission specialist in my area and he told me that you will often see folks pull a transmission, take it in for a rebuild, then re-install the rebuilt unit themselves and they have the SAME problem they had before, because the problem was in one of the sensors or wiring harnesses to begin with.

 

Dan

[silveradobobby]

Your having a line pressure issue which could be many issuses tranny or wiring! Check the TPS first it will have effect on line pressure. Dumb question but is the tranny fluid full after warm up? How long did you drive it after installing it? Another question whe nu installed the tranny did u make sure the torque converter was seated all the way if not could have damaged the pump and could be losing your line pressure from there.

[pennzoil29]

I would take it back to the tranny builder, and ask him to scan it. That should tell you wether or not your issue is sensor related. I was having a problem with my 4L80E, and it turned out to be the TPS. Good luck.

[kylespw80]

I changed the TPS and it did not make a difference in the shifting. While under the truck I noticed that the bare braided wire that is in the tube with the starter wires was broken. Would this be the ground the builder was talking about? Can I run a temporary ground from the battery to the transmission case to see if that helps?

[silveradobobby]

I changed the TPS and it did not make a difference in the shifting. While under the truck I noticed that the bare braided wire that is in the tube with the starter wires was broken. Would this be the ground the builder was talking about? Can I run a temporary ground from the battery to the transmission case to see if that helps?

 

 

Yes that would be the tranny ground. u can buy the bround straps at a local parts store.