4L60E shift problems

Hey folks, I am new to this forum, hello everyone. I have a 1996 Chevrolet Express van 2500 with a 4l60 e. The trans shifts and operates normally until the engine reaches normal operating temp, then the trans seems to go into "limp home mode" 3rd gear starts and no overdrive. I have replaced both the A and B solenoids, wiring harness was in good shape, fluid and filter, still the same. I am awaiting the ignition switch to change that out, wow $117! While driving the vehicle and with my scanner connected I can reset the codes and the Trans will shift into overdrive or when stopped I can reset codes and I can feel it shift down to first gear. the codes its showing is PO1886,Transaxle shift timing solenoid. PO700,Transmission control system malfuntion and PO1100 unknown. Where do I go from here. By the way when it is cold the trans shifts fine and when warm it shifts fine when reseting the codes, but codes come right back. Also where is the 30 amp fuse that is for the trans/ I have looked under in the under the hood fuse panel and nothing is listed as transmission related and all fuzes were good.

Code 1886 is a shorted or open 3/2 shift solenoid or circuit.
When code sets you will lose OD when hot and lock up.
MT

Code 1886 is a shorted or open 3/2 shift solenoid or circuit.
When code sets you will lose OD when hot and lock up.
MT I have already replaced the shift solenoids and the harness looked perfect. Is the 3/2 solenoid the same as the A and B?

I have already replaced the shift solenoids and the harness looked perfect. Is the 3/2 solenoid the same as the A and B? Does anyone sell the wiring harness?

3-2 solenoid is not the 1-2 A or 3-4 B.
It is a seperate solenoid.

The wiring and power feeds needs to be cecked with a good volt /ohm meter.

Also wiring plug in at solenoid and transmission case and on up to the transmission computer.

The 3-2 solenoid is located on front left side valve body.

MT 2500 you were correct, the 3/2 downshift solenoid was fried, swapped it out and it shifts like new again, thanks.

MT 2500 you were correct, the 3/2 downshift solenoid was fried, swapped it out and it shifts like new again, thanks.

Crm391
You are welcome
And thanks for posting back how it went and the fix.
Glad all is well and going good.
Good luck
MT

HELP..I think mine is a 4l80... 1999 express HD 3500. The speed gauge went on the frittz between 30-40 mph. The gauge would then bounce bet 20 and 40 as I sped up. That caused the trans to think I was under load so it pulled me out of OD. (mind you it rained the day it started)... The next day,It got worse... i think I was going faster so the speedo dropped down and it began free-wheeling . I could blip the throttle and iot would engage. Then it would do it again. I heard about the computer boxes corroding and getting wet... It was. Am I on the right track here????

No time or money!!?? HELP!!!!!

Thanks for advise !!!

RT

Hello I am new at this hope this is how it is done I have a 2002 chev express and want to change the trans from the 4L60 to the 4L80 with tow unit how can it be done thanks for the info ry

Hello I am new at this hope this is how it is done I have a 2002 chev express and want to change the trans from the 4L60 to the 4L80 with tow unit how can it be done thanks for the info ry

With a lot of time and money and parts it could be done.
But.
You need to start a new thread of your own for help with it.
MT