4L60E no lock in od

[dog73]

i got a 93 1/2 ton with 66k from a military auction. it's had problems with the transmission scince i got it in june. i've gone to two trans shops and had the fluid changed and the computer reset. now they say i need a new tourq converter? before the computer was reset it had 2nd and 3rd. now it's got all gears but feels like its slipping in and out of lock up in od. could it be a sensor? they hooked it up to there code reading computer and drove it around but no codes. it did show it slipping in and out of lockup in od.

[DennisG01]

Maybe someone else can chime in here, but I think there is supposed to be some kind of "friction modifer" fluid that is added to the trans fluid for proper operation. If this is true, maybe that special additive wasn't added?

[john8662]

There isn't a friction modifier for the transmission fluid, that's for the rear differentials with "limited slip" carriers installed, not the G80 even.

Anyways, does the transmission lock the torque convertor in 3rd? To test for this manually select 3rd or Drive and get to a steady speed with the trans already shifted to third. Then tap on the brake petal with your left foot while holding the accelerator with your right, the engine speed should increase slightly, then decrease again. This would indicate that the TC is locking in 3rd. Otherwise you can count shift events from a dead stop, you should get 4 shift feels in 3rd.

A bad brake switch could keep the TC from locking.

[DennisG01]

Thanks, John for the correction. I was only going on what I had come across on Bill Heath's website, not personal experience. Here's the link to what I was referring to: http://www.heathdiesel.com/P/HDP1044/

Would that stuff be for a different year truck?


ON EDIT: Oops - I just noticed that Dog73 is talking about a 4L60, not a 4L80. Shame on me for not reading closer!

[JohnC]

I'm moving this to the 6.2 forum since we're all 4L80E bigots here...

[blockw5chips]

I just paid $1500.00 to have the one in my wife's 96 burb replaced. The guy at the transmission shop said that there is a special additive that has to be put back in when the fluid is changed for the torque converter. He said alot of people go to these lube shops and the do a complete fluid change, but they don't add the special additive back in. Then they end up in his shop getting a new transmission. I don't know for sure if this is true(but this shop is the best in town). Good Luck:)

[farmerherb]

Lubeguard makes several friction modifiers, for Chry., Honda, Toyota etc. Never seen or read about one for GM but do have a generic modifier for all trans. The solenoid set for the 4L80E is about $80. I have 348,000 miles on my 4L80E I have changed the sythnetic oil several times solenoids once everything else is original.

[slugbait_69]

If it is your torque converter locking and unlocking when you are cruising replace your brake light switch, this is what was wrong with mine and it will not show up on a transmission diagnostic, the controller for the torque converter is wired through the brake switch to unlock it when you apply your breaks. The best part is it is a cheap part.

[dog73]

thanks for all the input i went to two more trans shops one said change the tourque converter 800.00 the other said change the trans 1800.00 i'm going to try the brake light switch. if that's not it then run it till it wont go no more.

[john8662]

Hmm, thanks for the link concerning the friction modifier, first I'd heard of it .

We all keep learning.

[farmerherb]

Torque converter for that trans. is not that expensive maybe 200 at the most. Check your area for Dacca/Detroit they reman. TCs.

[farmerherb]

John8662
Are you somewhere in a time warp or out in the Atlantic fishing? Your post time says 9:30 PM, I'm on the east coast its not 9:30 here now.

[john8662]

John8662
Are you somewhere in a time warp or out in the Atlantic fishing? Your post time says 9:30 PM, I'm on the east coast its not 9:30 here now.

I checked my settings under User CP and it's set for central standard time, GMT-6, you might check your settings as well.

In looking at that post, it says 4:30pm, which is accurate for me.

J

[moondoggie]

Good Day!

I was under the impression that GM never stuck a 4L60-E behind a 6.5TD, not even in 1/2 tons. Can anyone verify? This of course doesn't affect the troubleshooting information above.

I didn't mean to hijack this topic, but it is sorta related...

Blessings!

[john8662]

Good Day!

I was under the impression that GM never stuck a 4L60-E behind a 6.5TD, not even in 1/2 tons. Can anyone verify?

That statement is correct, no 6.5TD's in front of 60's.

For this scenario:

1993 1/2 ton, owner didn't specify the engine, but if it's a '93 and in a 1/2 ton it's a 6.2L. There were no 6.5TD's in half tons until 1994.

So... This truck does have a 4L60E in it because it's got a 6.2 non-turbo engine in it.

Clear as mud?

J