How I fixed my 4L80E

adumars · 11-11-2009, 06:25 PM

This post is in reference to my 1991 3/4 ton Suburban 6.2 liter/ 4L80E transmission:

Months of skipping and randomly shifting out of gear every time I hit a bump led to a self diagnosis easter egg replacement of speed sensors, wire harness inspections, and an internal harness replacement. Nothing would make the problem go away.

Finally, in a ditch effort to make the thing drive normally, I pulled the plug off the transmission, cleaned with WD40 and smeared a bunch of vasaline into the female end of the harness (the external) and plugged it back in. I have not had a shifting problem since (9 months and counting) - knock on wood!!

The shifting problems always occurred as I hit a bump. I guess the vasaline allowed a tight connection between the pins and their receptacles.

hotrodpc · 11-12-2009, 01:51 AM

Welcome to the forum !!! Great tip for a quick fix.

11-11-2009, 06:25 PM	#1
adumars Junior Member Join Date: Nov 2009 Location: Folly Beach, SC Posts: 1	How I fixed my 4L80E This post is in reference to my 1991 3/4 ton Suburban 6.2 liter/ 4L80E transmission: Months of skipping and randomly shifting out of gear every time I hit a bump led to a self diagnosis easter egg replacement of speed sensors, wire harness inspections, and an internal harness replacement. Nothing would make the problem go away. Finally, in a ditch effort to make the thing drive normally, I pulled the plug off the transmission, cleaned with WD40 and smeared a bunch of vasaline into the female end of the harness (the external) and plugged it back in. I have not had a shifting problem since (9 months and counting) - knock on wood!! The shifting problems always occurred as I hit a bump. I guess the vasaline allowed a tight connection between the pins and their receptacles.

11-12-2009, 01:51 AM	#2
hotrodpc Senior Member Join Date: Jul 2008 Location: OK Posts: 6,935	Welcome to the forum !!! Great tip for a quick fix. __________________ *Winners NEVER Quit , Quitters NEVER Win !!!*

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