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Can the 4L60E have good line pressure readings on the gauge 60-75 idle and 220 wot and good readings in all gears and still have leaking internal O-RINGS ? Sorry for dumb questions ,trying to learn a little about 4l60e. Thanks
Every perfect operating Automatic Transmission has some level of internal leaks.
Well if I turn the Pump up to make about 400 PSI...
It can have some pretty damn big internal leaks in multiple places and still show 75 PSI at Idle in at least one of the Gear Ranges...
and 220 WOT at some Engine RPM...
**** if I rev the Engine to 12,000 RPM in Reverse...
I might get like 280 PSI on the Gauge.
Can the 4L60E have good line pressure readings on the gauge 60-75 idle and 220 wot and good readings in all gears and still have leaking internal O-RINGS ? Sorry for dumb questions ,trying to learn a little about 4l60e. Thanks
To be able to tell if to have any significant internal leaks that will cause any issues, you will need to test line pressure while driving. You will need to monitor the pressures during after each shift. It is normal for pressers to drop on the shift but should recover quickly.
Can the 4L60E have good line pressure readings on the gauge 60-75 idle and 220 wot and good readings in all gears and still have leaking internal O-RINGS ? Sorry for dumb questions ,trying to learn a little about 4l60e. Thanks
To be able to tell if to have any significant internal leaks that will cause any issues, you will need to test line pressure while driving. You will need to monitor the pressures during after each shift. It is normal for pressers to drop on the shift but should recover quickly.
To be able to tell if to have any significant internal leaks that will cause any issues, you will need to test line pressure while driving. You will need to monitor the pressures during after each shift. It is normal for pressers to drop on the shift but should recover quickly.
I did that , last week , all the pressure readings in each gear were good, in D 321 all where from I remember around 175psi and reverse and park on wot got up to 220 I lifted the vehicle in the air on jacks and ran thru all the gears with the pressure line, hooked up to the side of the transmission on drivers side . My question also is why no engine light ?? Alot of 4L60E transmission with similar issue ! TCC ? VSS Engine control module? Corrosion ? Harness, 1= O-Ring , Some builders with transmission rebuilt and the same issue! Goes into Nuetral or no 3rd gear hmmm No Engine light! Did GM really put a dumb pcm in there at least give a fault for slipping🤣
You didn't say that you were having a problem, just that you wanted to learn a little about 4l60Es. If you are having a problem, we could answer your questions better if you could share a little info about your vehicle and the problem you are having.
2 weeks ago out of nowhere my truck goes into what feels like neutral ,but Scanner says its in 3rd , story is 2018 I installed a aTransgo sk **** kit and Pinless Forward Accumulator Piston Kit by Sonnax and Transgo 4L652ACM Transmission Piston, 1-2 Accumulator , it was great till 2 weeks ago, I hooked up transmission pressure gauge all readings seem good lifted vehicle and went thru all the gears pressure readings idle 75-220 wot and in all gears around 175-160 all seems normal there disconnected trans harness and same 1 and 2 second gear ok reverse ok but seems like it still goes into nuetral or is it really slipping ? The pcm should give a dam fault for a Slipping/gear monitoring smh! Vss? Tcc? O-Ring in valve body? Stuct 2-3 shift valve / shuttle valve ! Harness corrosion! I have read articles where they have rebuilt the transnsmission with new , just about all and still the problems checked and disconnected fuses still goes into 2nd and 1st , I am gonna check harnness and connectors next the transmission harness looks like it a tiny tiny bit of oil coming thru, also shouldnt the signal from the vss/tps and abs trigger a fault in the pcm
You should get several codes stored if the trans was run with the main harness disconnected. Does it seem to go into neutral when shifting, which gears are slipping and under what conditions does it go into neutral? Was the trans just rebuilt? Were the accumulator pistons replaced to try to rectify the problem you are currently having?
It is hard to do a good line pressure test on jackstands, the vehicle needs to be driven.
I did get codes! But because of the harness disconnected! Ok I found hopefully some helpfull info off alldata for help , Im new to this forum, so Im gonna try to post tech Bulletin and if it does not help me hopefully it helps others👍 Hopefully helps !👍
Lol ! Earlier today , I recieved this a sonnax shift valve 2-3 #77754 that I was already suspecting and had ordered last week and a servo kit 2nd gear and 4th servo here go pics.
Also it talks about solenoids . and man ,I wouldnt be surprised ,if some dam O-RIng might ,be the culprit 😐 or a solenoid screen fell off or its bad, also there is the manifold switch , etc more and more crap, oh well if not, its a transmission sooner or later for everyone 💣😈
Is this a rebuild or a OE unit with xxx miles?
Did you replace the accumulators? For what issue?
4L60E's are built with some what old school technology. They didn't think of or incorporate slip into the equation until 2007 when they added the ISS. With that said.
Both solenoid "A" & "B" are on for 1st.
Solenoid "A" turns off for 2nd, Solenoid "B" stays on.
Both "A" & "B" solenoids are off for 3rd.
Solenoid "A" comes back on for 4th.
Disconnecting the fuse or the 20 pin case connector should give you limp mode. Limp mode is 3rd gear with a manual 2nd.
So if you have a 2-3 slip or 2-nothing. Your solenoids have all changed from on to off and that say's they are working. That scenario usually means you have a 3-4 clutch failure. 3-4 clutch failure is the #1 failure in a 4L60E transmission.
I did see that, when I had the Autel hooked up monitoring the shift solenoids, I might have to get a rebuilt or used low mile tranny , but at least I want to try, before the next transmission. Also I want to install some good parts on the next one and the more research , possibly maybe I will have a better combo, that will help to get it to last longer, miss driving my truck already Also when I disconnected the fuses on my particular truck/ could be because of a production split but my truck goes into 1st and 2nd gear and reverse same as disconnecting the harness connector from the transmission,which I also did. I have not checked at the pcm connector yet for corrosion as a friend had a 1999 tahoe with erratic shift problems and found the culprit there. Also I have not opened up the pan yet and have not disconnected the VSS , I work alot and commute sucks , need some time to work on my truck beside just 5 or ten minutes here and there! Thanks Again Kool Forum
With electrical power disconnected from any year model 4L60E you should not have 1st gear. You still have not told us any specifics of what is going on with your trans. A general its going into neutral or slipping is not enough info for anyone to really help you. When is it neutraling out, when is it slipping?
With electrical power disconnected from any year model 4L60E you should not have 1st gear. You still have not told us any specifics of what is going on with your trans. A general its going into neutral or slipping is not enough info for anyone to really help you. When is it neutraling out, when is it slipping?
I know it doesn't apply here, but for anyone that reads this thread in the future maybe searching for similar issues.
The above highlighted in red is accurate UNLESS you have a transgo 1-2 shift valve installed. In which case, even without power, if you pull the shifter to manual low, you WILL have 1st gear.
As for the highlighted in green I agree with bbond. We need better explanation here.
Actually, with the transgo valve installed "limp mode or harness unplugged" pulling to manual 1 will result in a brake like bind up as the 3-4 clutch will remain on. It will act sorta like a weaker trans brake as with throttle you can pull through it but burning up the 3-4 clutch. If you do have a normal feeling 1st gear then the 3-4 clutch is already fried. Frank@performbuilt.com
negative--manual low with or without power to the trans will be 1st gear with the low/rev clutches on for engine braking
the transgo valve forces the 1-2 shift valve inboard (similar to solenoid ON) even with the solenoid de-energized
And D2 oil will keep the inner portion of the 2-3 valve lineup inboard regardless of solenoid...which blocks the feed from 2nd to 3-4 signal and exhausts 3/4 signal at the shift valve... oil aka no 3/4 clutch apply. 3/4 clutch is actually exhausted.
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4L60E $questions 
Also when I disconnected the fuses on my particular truck/ could be because of a production split but my truck goes into 1st and 2nd gear and reverse same as disconnecting the harness connector from the transmission,which I also did. I have not checked at the pcm connector yet for corrosion as a friend had a 1999 tahoe with erratic shift problems and found the culprit there. Also I have not opened up the pan yet and have not disconnected the VSS , I work alot and commute sucks , need some time to work on my truck beside just 5 or ten minutes here and there! Thanks Again Kool Forum 
