91 R2500 4L80E problem - The 1947 - Present Chevrolet & GMC Truck Message Board Network

91r2500 · 03-10-2018, 08:51 PM

Hello, Welcome to my first thread

I am having an odd issue with my 4l80E.
When shifting automatically it skips second, it shifts through all other gears 1-3-4, does not slip, nor give any other problems.
When I shift it manually all gears work 1-2-3-4 no problem. It will not automatically downshift to 2nd either, 4th to 3rd is fine and if I go slow enough it will go into 1st as well, it will downshift to second if I manually put the shifter into 2nd though.

I have replaced all of the solenoids and wiring harness in the trans., rewired the external harness (someone did the conversion to the newer harness but the connections looked iffy) While resplicing the connector I checked to make sure that the wires were in their proper places.

Anyone have any ideas?
Thank you in advance for any help.

03-10-2018, 08:51 PM	#1
91r2500 Registered User Join Date: Mar 2018 Location: Melrose, Florida Posts: 1	91 R2500 4L80E problem Hello, Welcome to my first thread I am having an odd issue with my 4l80E. When shifting automatically it skips second, it shifts through all other gears 1-3-4, does not slip, nor give any other problems. When I shift it manually all gears work 1-2-3-4 no problem. It will not automatically downshift to 2nd either, 4th to 3rd is fine and if I go slow enough it will go into 1st as well, it will downshift to second if I manually put the shifter into 2nd though. I have replaced all of the solenoids and wiring harness in the trans., rewired the external harness (someone did the conversion to the newer harness but the connections looked iffy) While resplicing the connector I checked to make sure that the wires were in their proper places. Anyone have any ideas? Thank you in advance for any help. Last edited by 91r2500; 03-10-2018 at 08:53 PM. Reason: missing info.



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