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The other day my S10 started taking awhile to shift into 2nd gear.
Transmission is a 2005 4L80e with a 3600 stall Yank converter and Transgo HD2 shift kit. Has 5k miles on it with no issues so far.
Going through the data logs its taking about 2-3 seconds after the ECU commands the shift before it actually goes into 2nd gear.
Looking through my ATSG manual the components that would cause this could be either the output speed sensor, input speed senor, pressure switch manifold, or the calibration in the ECU.
I data logged the input and output speed sensors and everything looks normal so I am assuming that the sensors and wiring are okay there.
Since the ECU is commanding the shift at what seems like a correct time I believe I can rule out the calibration which leaves just the pressure switch manifold and its wiring left as the most likely culprits.
I will verify continuity tomorrow from the ECU to each of the pins on the round connector on the side of the trans but if they all check out is my next step to pull the pan and verify the bolts for the pressure switch are torqued correctly?
I have attached the VCM scanner file if someone wants to review the issue.
I also added 2 screenshots below. The first one is the first frame where the "Trans Current Gear" goes from 1 to 2 and the second one is where the RPM starts to actually drop.
Thanks!
Shane
Last edited by zildjian4life218; Nov 23, 2019 at 07:30 PM.
Reason: forgot to add 4l80e to title
Check the fluid level (after checking proper dipstick calibration) and then get rid of the HD2 kit. We quit using TransGo VB kits years ago and this was one of the reasons.
Check the fluid level (after checking proper dipstick calibration) and then get rid of the HD2 kit. We quit using TransGo VB kits years ago and this was one of the reasons.
I actually had issues with it last year where it would make a squealing noise above certain rpms and it ended up being the fluid level issue. After some research I found that the factory mark was 5/8” below where it needed to be so I pulled the pan and measured and remarked the dipstick so it should be correct now.
is there something in the shift kit that would wear out over the course of a year?
Do you see the pressure switches go bad often or think its worth check if it could be leaking before I pull the trans and put a different shift kit in it?
I actually had issues with it last year where it would make a squealing noise above certain rpms and it ended up being the fluid level issue. After some research I found that the factory mark was 5/8” below where it needed to be so I pulled the pan and measured and remarked the dipstick so it should be correct now.
is there something in the shift kit that would wear out over the course of a year?
Do you see the pressure switches go bad often or think its worth check if it could be leaking before I pull the trans and put a different shift kit in it?
We've been preaching about fluid level for years as well and the industry is starting to listen.
The shift kit can cause the clutches to get glazd over time.
We've been preaching about fluid level for years as well and the industry is starting to listen.
The shift kit can cause the clutches to get glazd over time.
Pressure switch doesn't often go bad.
If the wiring was pinched or broke for some reason would it eventually shift into 2nd or not at all?
the other thing the ATSG manual mentions is that if the pressure switch was not torqued all the way correctly or the bolts came loose it could be bleeding off the pressure.
it’s just strange that it was working fine then one day just started acting up
I verified continuity on all of the wires today and everything checked out.
I dropped the pan and checked that the pressure manifold was torqued correctly (ATSG manual says 116 in/lbs). I am going to drop it now and verify that the orings on the backside of it are intact and not leaking or something.
So looking at the powerflow chart and shift solenoid pattern from my ATSG manual I have come to 3 conclusions. https://forum.efilive.com/showthread...rence-Material
Since the issue happens whether the shifter is in D2, D3, or D4 It will have to be something that each of them share.
One being the release of Solenoid A. Maybe there is something wrong with it and it is not releasing when it should when under pressure? I did test this by using my HPTuners to manually command each of the gears and I could hear the solenoid release when I commanded second after commanding 1st.
Second being the intermediate clutches are applied from 1st to 2nd.
3rd being the low roller clutch going from holding to overrunning.
Am I understanding this correctly? Anything a pressure gauge would help with if I installed one and did some more testing? Just trying to avoid tossing another transmission in without understanding what went wrong and why it went wrong.
I am starting to think that my initial approach of a delayed shift was wrong. The troubleshooting section of the ATSG manual seems to only blame electronics which would mean its talking about the computer delaying the command of the shift not so much that the trans is taking awhile to complete the shift once it’s been commanded.
Did you perform the stupid pressure relief modifications in the Transgo instructions?
Have you measured line pressure?
You are going to want to see how the line pressure gauge acts during the 1 to 2 shift.
That is where I would start.
Yes I performed all of the steps in the instructions. I believe you are talking about the one where you drill a hole between 2 passages in the pump?
I will be picking up the pressure gauge Tuesday after work so hopefully should have some data by Wednesday
Well that would explain the soft 1-2 shift. The intermediate clutches and steels are toast. Now the fun part to figure out why they failed. This was from a 150k+ mile vehicle from the junkyard that was running and driving when it got t-boned.
Just About the only thing that can cause smoked intermediate clutches is low fluid level. They have so much piston and clutch capacity that at prettymuch any power level...if there is line pressure...they will hold.
Look at the sealing ring surface of the forward drum, they like to ring cut a lot. The last 4 out of 5 builds I did needed a drum. There is a groove around the feed hole that is made there. It should be smooth above and below the groove. For standard rebuilds I use TransGo SK 4L80E & HD ring kit for this application and ream the AFL valve.
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Troubleshooting delayed 1-2 shift 4L80e 
