JordanR
Newbie
Hi All!
I am new to the platform and helping my friend with his truck. It is presenting with the ever-popular issue of not wanting to shift, and revving high but not speeding up past ~30 mph. This is the list of things I have read about in all the forums as a possible cause:
3-4 clutch pack
Middle case leak in the 2nd gear apply circuit
Shift solenoid(s)
EV clutch fan
3rd and 4th actuator piston
3rd accumulator check ball
PCM wiring harness
Transmission internal wiring harness
Loose wire somewhere
I checked fluids and every fuse. There were no trouble codes.
I read a guide that suggested removing the GREEN trans connector to force the truck into limp mode. This was supposed to show us whether the 3-4 pack was fried- if it was the truck should slip and not go anywhere.
Well, my clever self disconnected the VSS instead. My friend drove it around the parking lot as planned before it occurred to me I did wrong. I reconnected the VSS and waddayaknow, it shifted as it should now! Very much the opposite of what I expected. However, he did get ABS dash warnings and I lost some credibility for pulling the wrong connector. I will add that this was a while ago, so I can't remember if it shifted right immediately after I pulled the VSS or only after I plugged it back in.
Now, why would pulling the VSS and plugging it back in allow the truck to shift as it should past 30 mph (we think, we didn't get on roads to go much faster than that, but the trans acted like it was civilized again)? Also, this was temporary; after a while it struggled again. Finally, it has returned to the original state of revving past 30mph with no shift.
My next step was to try to use some piercing leads and https://www.ericthecarguy.com/kunen...nswered-Here/51667-4l60e-tranny-issues#100255 this guide from ericthecarguy to see if there is a problem with the internal wiring harness.
However, I am way out of my competence now that we are testing circuits, and I can easily see myself doing the procedure wrong and getting an unreliable result. I also don't know if this is the right direction. Finally, I don't want to drop the trans, and I live far away from my friend/his truck so I have been accumulating as much as I can into a flowchart since learning and then trying one thing at a time won't jive with our logistics.
Does the intermittency associated with my fiddling with wires provide a clue? Am I on the right track? Will we ever get this thing fixed??
I am new to the platform and helping my friend with his truck. It is presenting with the ever-popular issue of not wanting to shift, and revving high but not speeding up past ~30 mph. This is the list of things I have read about in all the forums as a possible cause:
3-4 clutch pack
Middle case leak in the 2nd gear apply circuit
Shift solenoid(s)
EV clutch fan
3rd and 4th actuator piston
3rd accumulator check ball
PCM wiring harness
Transmission internal wiring harness
Loose wire somewhere
I checked fluids and every fuse. There were no trouble codes.
I read a guide that suggested removing the GREEN trans connector to force the truck into limp mode. This was supposed to show us whether the 3-4 pack was fried- if it was the truck should slip and not go anywhere.
Well, my clever self disconnected the VSS instead. My friend drove it around the parking lot as planned before it occurred to me I did wrong. I reconnected the VSS and waddayaknow, it shifted as it should now! Very much the opposite of what I expected. However, he did get ABS dash warnings and I lost some credibility for pulling the wrong connector. I will add that this was a while ago, so I can't remember if it shifted right immediately after I pulled the VSS or only after I plugged it back in.
Now, why would pulling the VSS and plugging it back in allow the truck to shift as it should past 30 mph (we think, we didn't get on roads to go much faster than that, but the trans acted like it was civilized again)? Also, this was temporary; after a while it struggled again. Finally, it has returned to the original state of revving past 30mph with no shift.
My next step was to try to use some piercing leads and https://www.ericthecarguy.com/kunen...nswered-Here/51667-4l60e-tranny-issues#100255 this guide from ericthecarguy to see if there is a problem with the internal wiring harness.
However, I am way out of my competence now that we are testing circuits, and I can easily see myself doing the procedure wrong and getting an unreliable result. I also don't know if this is the right direction. Finally, I don't want to drop the trans, and I live far away from my friend/his truck so I have been accumulating as much as I can into a flowchart since learning and then trying one thing at a time won't jive with our logistics.
Does the intermittency associated with my fiddling with wires provide a clue? Am I on the right track? Will we ever get this thing fixed??
