4l80e no overdrive

[Schurkey]

Are you sure it's a gear-ratio issue and not a torque converter clutch problem?

The converter clutch is locked-out if the computer senses misfire.

'97 K2500 7.4L. I "fixed" my transmission and my engine misfire by replacing a single cracked spark plug.

 

[NickTransmissions]

Anyone here experienced losing 3rd or 4th gear on their 4L80E 4WD Transmission? I have a 95 GMC Suburban K2500 and was reving at 3,000 RPM at 45-50mph with higher RPMs the faster I go....redline on my 454 motor is at 4,000. After i got off the freeway I restarted the engine and then shifted from 2Hi to 4Hi and back to 2Hi. This temporarily/permanently fixed the issue? Any idea what could have caused this?

I think everyone who has ever owned a 4L80E-euqipped vehicle has had some experience with losing 3rd and 4th gear or know someone who has.

Do you have any problems in Reverse at all (slipping, delayed engagements, etc)?

Also, did you shifting the transfer case from 2Hi to 4Hi and back to 2Hi after a power down and restart permanently fix the issue or just temporarily fix it? Can't be both.

 

[whataTRUUUCK]

I think everyone who has ever owned a 4L80E-euqipped vehicle has had some experience with losing 3rd and 4th gear or know someone who has.

Do you have any problems in Reverse at all (slipping, delayed engagements, etc)?

Also, did you shifting the transfer case from 2Hi to 4Hi and back to 2Hi after a power down and restart permanently fix the issue or just temporarily fix it? Can't be both.

Nope, I never have problems in reverse at all (slipping, delayed engagements, etc). I shifted from 2Hi to 4Lo/4Hi after restarting the truck, but the issue happend a couple times again later in the week. From what I've researched, It could be a VSS or shift solenoid/shift solenoid harness issue if im lucky

 

[NickTransmissions]

Nope, I never have problems in reverse at all (slipping, delayed engagements, etc). I shifted from 2Hi to 4Lo/4Hi after restarting the truck, but the issue happend a couple times again later in the week. From what I've researched, It could be a VSS or shift solenoid/shift solenoid harness issue if im lucky

If you're in 2Hi or 4Hi and you're false neutral in 3rd, it's likely direct clutch...No upshift at all would be something potentially solenoid-related. It could also be your VSS...Any problems with your speedometer? Intermittent VSS failure can show as false neutrals at higher vehucle speeds as the bad sensor isnt genersting any voltage or insufficient voltage... If you do replace the speed sensor, buy an OEM sensor - DO NOT buy one from auto parts stores or Rock Auto, Amazon etc unless it's an OEM GM part. Im not sure who makes the Tcase sensors (AC Delco, Delphi, Rostra?).

You can also drop the pan to see what's on the bottom. If you see a bunch black clutch material and/or metal just yank it out for overhaul.

 

[whataTRUUUCK]

If you're in 2Hi or 4Hi and you're false neutral in 3rd, it's likely direct clutch...No upshift at all would be something potentially solenoid-related. It could also be your VSS...Any problems with your speedometer? Intermittent VSS failure can show as false neutrals at higher vehucle speeds as the bad sensor isnt genersting any voltage or insufficient voltage... If you do replace the speed sensor, buy an OEM sensor - DO NOT buy one from auto parts stores or Rock Auto, Amazon etc unless it's an OEM GM part. Im not sure who makes the Tcase sensors (AC Delco, Delphi, Rostra?).

You can also drop the pan to see what's on the bottom. If you see a bunch black clutch material and/or metal just yank it out for overhaul.

Thanks for the input! Yea my speedometer works perfectly fine....can it still be the VSS despite that? Unfortunately im gonna have to push myself to drop the pan to inspect for metal shavings/chunks despite the fluid being clean...if im lucky tho it could be a clogged trans filter....id rather not drop the pan twice so i might be the solenoids/harness before I do this job, in case I decide to change them out while I'm in there

 

[NickTransmissions]

Thanks for the input! Yea my speedometer works perfectly fine....can it still be the VSS despite that? Unfortunately im gonna have to push myself to drop the pan to inspect for metal shavings/chunks despite the fluid being clean...if im lucky tho it could be a clogged trans filter....id rather not drop the pan twice so i might be the solenoids/harness before I do this job, in case I decide to change them out while I'm in there

Id replace all those electrical components if you're dropping the pan. 4L80Es are notorious for problems with leaking harness plugs, shift solenoids coming apart, etc...cut the filter open to see if it's clogged and what's caught inside of it.

 

[whataTRUUUCK]

Id replace all those electrical components if you're dropping the pan. 4L80Es are notorious for problems with leaking harness plugs, shift solenoids coming apart, etc...cut the filter open to see if it's clogged and what's caught inside of it.

O boy....sounds like a fun upcoming project‍