4L80E Transmission

[bulldogchance]

Can someone tell me the most comman reason why this transmission will not up shift to O/D, shifts fine from 1st thur drive.

[Garth J]

I had a shifting problem and after a lot of checks it turned out to be the fluid sensor on the thermostat housing. It looks like a temp sender but it senses fluid and wont let the tranny shift into o/d with low or cold fluid its only about $25 so I would start there...Garth

[DragNasty]

From what I hear, The bushings on the OD gear are bad about wearing out and not letting overdrive clutchs hold. Mine in my other dually would start slipping when It got hot.

[Steeveo]

340,000 K's and only problem I have is a torque converter stutter when it tries to unlock in drive and OD.

[6.5 on da bayou]

Couple of years ago, My dually would be traveling fine down the road in O/D and then violently shift into drive. Ended up being the fluid temp. sensor that Garth was talkin bout on the thermostat housing.

[bulldogchance]

Good morning ,well I changed the switch on the houesing and guss what your right it still does not shift into O/D. Any other reason it will not go into O/D.Thanks to all trying to help.:confused:

[Garth J]

You got me stumped so best solution is ask Walt He will know...Garth

[Scrufdog]

Good morning ,well I changed the switch on the houesing and guss what your right it still does not shift into O/D. Any other reason it will not go into O/D.Thanks to all trying to help.:confused:

What year is your truck? If its OBD-II (96-up) then you changed the wrong temp sensor.

My internal tranny temp sensor is part of a small 'module' of pressure switches and the temp sensor. Sits right in the open after you drop the tranny pan. Costs less than 60 bucks, easy to change once the pan is down.

The ECU wont let the tranny shift into O/D until the tranny is warm, so its reads the tranny temp itself from that internal sensor, instead of relying on the engine's water temp.

[bulldogchance]

It is a 1993 2500 4x4.:confused:

[bulldogchance]

AAMCO said that the B sol. is suck on , the T/C is not locking up, it coded 22,85,86 and I should spend 2300.00 and get a rebuild. WHAT A SURPRIZE.

[Steeveo]

Gee I wish I could get that code on mine, then the TC would not be shuttering when trying to unlock. LOL...where can I locate the b sol.?

[bulldogchance]

The B sol. is in the pan on the valve body.

[RAYMONDK]

Is it not shifting into OD (4th gear) or is the converter not locking up? The temperature control only prevents lockup till warm. The shift pattern is not affected. The shift signals come from the PCM so you can check it at the PCM with a volt meter. If it does OK voltage wise, then check the lock-up solenoid with an ammeter. They draw about 1 amp or disconnect and measure the resistance (about 14 ohms) You can't do it without a manual. I have a 4T80E in my 93 Eldo which is the transverse version of the 4L80E which is an electronic rendition of a 700R4. The solenoids have plastic bodies and they all break sooner or later. Mine broke at around 95,000 miles leaving it in second gear with my wife driving 70, it red lined and cutback. Transmission shops wanted $600-$2500 to fix it. I bought the factory upgrade kit for $48. and fixed it myself in 5 hours or so.

[bulldogchance]

It does not shift from 3rd into 4th,I just bought all new sol. (4) and a trans-go shift kit, I will replace them and if the pan is off might as well put in a shift kit and a deep pan. Here the a&b sol.are $18.00 each the TCC sol. is $38.00 and the PCV sol. was $48.00

[RAYMONDK]

Good descision on the shift kit. I've installed near 50 of them with never a problem. They know exactly what they are doing at Transgo. They also have great technical assistance. All of the ones I installed returned the transmission to almost like or better than new operation and I never had to touch one again. My 83 Suburban 6.2 700R4 which was a famous failure now has over 170,000 miles in it and it still hits OD like a power shift at 80 MPH.

[bulldogchance]

I changed all 4 solenoid over the week end & installed a Derale deep pan. The transmission now shifts into O/D I need to reset the TPS on the IP the transmission stays in 1st & 2nd a little to long.

[DetroitDan]

This is what I've been having also. Sometimes I can drive a ways in OD, and when it tries to lock up the TCC it just start slipping. Other times as soon as it shifts out of 3rd into OD it slips. I replaced the ECT on the thermostat housing, before I knew it wasn't the right one for my 97. I also changed the TCC solenoid and really hoped that would fix it, but no luck. I was going to replace the VSS, but a mechanic told me that while the VSS may make the trans not shift into OD, I would also not have a speedometer, which I do. So I didn't change that. I couldn't find a listing for the correct temp sensor in the pan. I was told about the Sonnax repair kit for the TCC, but I've heard good and bad so I'm not sure if I should try it. I am very close to buying a reman and swapping this tranny, but I would like to know that I exhausted all other avenues first. So is there another solenoid I should change? Or the temp sensor? What do you think?

[Sundance]

Good descision on the shift kit. I've installed near 50 of them with never a problem. They know exactly what they are doing at Transgo. They also have great technical assistance. All of the ones I installed returned the transmission to almost like or better than new operation and I never had to touch one again. My 83 Suburban 6.2 700R4 which was a famous failure now has over 170,000 miles in it and it still hits OD like a power shift at 80 MPH.


What is a "shift kit"?:confused:

[bulldogchance]

What is a "shift kit"?:confused:Trans-go make a kit that change the fluid path in the valve bodied for the transmission go to the web page trans-go.com. it worked well for me.:D

[daustin]

This is what I've been having also. Sometimes I can drive a ways in OD, and when it tries to lock up the TCC it just start slipping. Other times as soon as it shifts out of 3rd into OD it slips. I replaced the ECT on the thermostat housing, before I knew it wasn't the right one for my 97. I also changed the TCC solenoid and really hoped that would fix it, but no luck. I was going to replace the VSS, but a mechanic told me that while the VSS may make the trans not shift into OD, I would also not have a speedometer, which I do. So I didn't change that. I couldn't find a listing for the correct temp sensor in the pan. I was told about the Sonnax repair kit for the TCC, but I've heard good and bad so I'm not sure if I should try it. I am very close to buying a reman and swapping this tranny, but I would like to know that I exhausted all other avenues first. So is there another solenoid I should change? Or the temp sensor? What do you think?
On the '93 models, the temp sensor is built into the internal wiring harness, not a seperate sensor. (According to the FSM's from GM) I bought a 4L80E wiring harness on ebay for about $110 (included internal & external) because i suspected the temp sensor on my '93. I have just about the same problem on my '93 3500. Hopefully this weekend i'll get time to get my new shift solinoids and harness installed in mine. I also have a coolant leak which i'll chase as well. Good luck.
Don

[daustin]

I changed all the solinoids on my 4L80E last weekend, now it shifts fine and OD - 4th works like it should and the TCC locks up. I found a kit on ebay for about $110, i changed the filter & fluid as well. I went to AAMCO first and they wanted to sell me a rebuild for $2100. I also talked to my buddy who does tranny work, he suggested changing the solinoids first and it worked.
Don

[bulldogchance]

I changed all the solinoids on my 4L80E last weekend, now it shifts fine and OD - 4th works like it should and the TCC locks up. I found a kit on ebay for about $110, i changed the filter & fluid as well. I went to AAMCO first and they wanted to sell me a rebuild for $2100. I also talked to my buddy who does tranny work, he suggested changing the solinoids first and it worked.
DonIsnt AAMCO nice, They only wanted 2300.00 to "fix" mine.

[daustin]

Yea, like a friend once told me "AAMCO dosen't think you need a new trans, just a rebuilt one" they want to rebuild everything, not just fix it. LOL
I'm happy with my 3 hours work, parts under $200 including a new internal wiring harness and a nice shifting 4L80E. I replaced the wiring harness 'cause the computer kept telling me "Hi fluid temp" which means it thinks it's over 300 degrees!! I couldnt buy just the temp sensor, it's made into the harness but i found a new harness on ebay. Fixed my problems thus far, time will tell how long it lasts. hehehe
Don