4L80E Solenoid, Pressure Switch, Speed Sensor Testing and Diagnosis

I walk the view through electrical/electronic testing and diagnosis via a multi-meter for 4L80E transmissions while the transmission is still in the vehicle or otherwise fully assembled. I also give an overview and demonstrate test procedures on he pressure switch manifold assembly, which has to be tested directly when the transmission pan is removed.
The video has tables and diagrams to aid the tester during the process and should give anyone looking to diagnose or troubleshoot a good understanding of what to do and how to do it. It's also helpful for anyone looking to purchase a good used transmission that has a multimeter with them when checking out 4L80Es for sale at junk yards, swap meets or on Craigslist.
4L80E ATSG Manual: file:///Users/nicholasnuciforo/Downloads/4L80E%20ATSG.pdf
Converting 1991-1992 valve body and spacer plate to work with 1993/94+ non-vented EPC produced by Borg Warner: res.cloudinary...
Tech Notes: ATSG states the wiring harness changed in 1993; torque compensator valve eliminated after 1993; however, if you have a 1991-1993 model year unit that has the earlier harness/VB, you can install a Rosta harness, part number 34446AK (works on all years 1991-2003), updated BW non-vented solenoid and adapt the VB and plate to work with the updated EPC (See Transgo link for instructions below). Valve bodies that use the initial vented electronic pressure control solenoid (EPC), produced by Bosch, will need to be adapted to work with the updated Borg Warner/Holly EPC. See page 5 of Transgo's SK-4L80E shift kit instructions on how to do this procedure: res.cloudinary...

[@theproofgiver007]

My 4l80e is throwing a p1810. Takes about 60 seconds to shift into any gear. Just revs like neutral when in any gear.When it does it shifts into gear, it shifts great every gear. Im leaning towards the pressure switch. Also no speedo reading. I’m doing this test today. Thank you!!

[@nickstransmissions]

Hi Sean, yep sounds like TFP aka pressure switch manifold. I believe when they fail you will have delayed engagements into gear because the switch isn't communicating the signal to the PCM indicating manual valve position (or it's doing it 'late'). Another consideration is the transmission wiring harness itself...Disconnect the case connector plug from the internal harness on the outside of the transmission and look to see if any fluid is leaking through the connector...If so, replace the wiring harness as well...Ohm out the rest of the solenoids to confirm they are working properly while you have the pan off...

[@silentbravo]

Thanks, looks like valuable troubleshooting info

[@nickstransmissions]

Thanks, SB!

[@hybridmusclegarage4590]

Awesome as always!!

[@nickstransmissions]

Thanks, man!

[@chuck3441]

Great job

[@nickstransmissions]

Thank you, Chuck. Appreciate the kind words.

[@ralphpomm4943]

I have a higher almost fluid sound when going into drive or reverse. In park and neutral the sound goes away. It's in a 1995 chev G30 454. The van other then the odd sound seems to shift normally. I just recently bought this van. Any idea?

[@nickstransmissions]

Hi Ralph, Unfortunately noises are nearly impossible to diagnose over the net as everyone will have a different interpretation of what they're hearing and way of describing the noise. So unfortunately, I have no idea what it could be beyond perhaps front pump but just a wild-ass guess. Check underneath thoroughly to rule anything else out then perhaps unbolt the converter from the transmission and spin it in place...If it's making any unusual noises or is otherwise very difficult to turn (it shouldn't be), yank the trans and replace the converter. Again, without drivability symptoms to go on since there's none to report at the moment, I'm simply guessing at this point.

[@ralphpomm4943]

@@nickstransmissions thank you

[@nickstransmissions]

You're welcome, Ralph.

[@GipDuece]

You don’t have a video on replacing the temp sensor do you?

[@nickstransmissions]

I do - the temp sensor is integrated into the wiring harness so you simply replace the transmission's wiring harness...See my 4L80E Basic Rebuild Series, PT3 for how to install the harness/temp sensor assembly: kzbin.info/www/bejne/iKfZpKKugcaEe9E Skip to 20:17 where I begin installing the harness.

[@jf4872]

A common problem with the 4L80E is fluid leaking into the connector. That requires dropping the pan and replacing the internal wire harness.

[@nickstransmissions]

Yep, very common. I mention it frequently in my videos and on the various forums I'm on.

[@sagemata5756]

Tonight I randomly had a “fluid temp warning” light come on. Confirmed pump was working and fluid level was good. Is there a physical temp sensor on the VB I can change? I have a parts trans. Coming to a stop my scan tool says 302° but when confirming with infrared temp gun TC, pan and cooler read no higher than 180°

[@nickstransmissions]

Hi Sagemata, your transmission fluid temp sensor for 4L80Es is on the wiring harness itself so you just need to replace the harness. Yea, there's no way those temps hit 300 degrees - you'd feel that and the trans would have melted down, lol. It's a good idea to replace the harness as those wear out and cause a variety of problems including shorts leading to limp mode (2nd and reverse only), leaks through the harness connector, not to mention trans temp sensor failures.

[@sagemata5756]

@@nickstransmissions update. The harness touched the exhaust pipe and burnt a few wires. All fixed and going good now.

[@mattandkatchristie2552]

Great video!!! My 4l80 speedometer jumps way way to high even at low speeds and won't shift into over drive.. code p1860 . Please help

[@nickstransmissions]

Thanks, Matt! P1860 is your PWM solenoid which inserts into the valve body next to the electronic pressure control solenoid. Test the PWM solenoid following my instructions in the video...

[@teeandrea7580]

When you tested. a b c. You grounded to the table. Was the component also grounded to the table .it looked like it was on a rag.

[@nickstransmissions]

Thank you for watching, Tee Andrea. I filmed that about two months ago so don't recall the specific details but if there was a rag on the bench, the pointed probe would have went right through it and grounded to the steel bench top. I would have seen a disruption on the meter if the rag created a barrier to grounding the circuit.

[@timwalters8264]

I have lost OD in mine. 1-3 no problem. Shifts normal. Do you have any ideas? Thank you.

[@nickstransmissions]

Hi Tim, sorry to hear...Sounds like the OD clutch pack has burnt...Drop the pan, see what's at the bottom..If the fluid is black, smells burnt then you'll need to yank it for overhaul..You can check out my 4L80E rebuild videos for a thorough step by step review of the process.

[@jf4872]

@@nickstransmissions What if there are no signs in the fluid?

[@nickstransmissions]

Highly unlikely if the overdrive clutch burned; fluid will black, smell real bad. If he just doesnt upshift to fouth (ie pcm is not commanding or it is but valve body/solenoids arent responding, that's a different problem with different diag procedure. Bi-dir Scan tool with live data can be used to see if a shift is being commanded and/or command it to rule in or out electrical/electronic problems.

[@jf4872]

@@nickstransmissions You have a recommendation for such scan tool for OBD-1?

[@nickstransmissions]

For GM vehicles, I'd look for a TECH-1A for anything 82-91 and a TECH2 for anything 92-2013. If you need a tool that works across multiple makes/models, look at Snap On's scan tools. Their ODB1 line up uses multiple ALDL adaptors for each manufacturer and is compatible with most of their Modis, Solus and Verus line of scan tools.

[@TurboMalibuV6]

Is there an actual pressure sensor in the transmission that sends a pressure signal to the ECU? I don't see a pressure output pin in that diagram. Or does the ECM just do a calculated guess as to what the pump pressure should be even though the pressure might be physically low using a mechanical gauge?

[@nickstransmissions]

The closest thing would be the continuity signal from the electronic pressure control solenoid. The ECM doesn't monitor literal trans pressures beyond what it has programmed to max the line pressure when it detects a fault that requires putting the transmission into limp mode. Are you having issues with your trans? If so, what's happening?

[@atsemp10]

I’m having an issue with mine and I can’t fine the issue it won’t shift past 2nd

[@nickstransmissions]

It wont upshift from second gear or when it does, it feels like the vehicle is in neutral?

[@BayWop]

@@nickstransmissions have you found the issue? My 4l80e is standalone using the ncr controller but it seems like it wont go pass 2nd

[@dannymaldonado8802]

Looking at your videos is very helpful. 2008 Cadillac Escalade esv 6.2. it will drive a little then stop going I have discount my battery then it moves a little again. Code p2723 goes. Wat u think. Thank you so much.

[@nickstransmissions]

Thanks for watching and the kind words, Danny! Assuming you have a 6L80 in the Escalade, that code is for one of the clutch pressure control solenoid #5 which is on in 1st-4th gear and based on your description, it sounds like it has failed thus creating pressure loss inside the trans thus little to no movement. I'd drop the pan and begin continuity testing the individual solenoids, starting with CPC #5. If it's indeed no good, you will need to replace the entire TEHCM as the solenoids themselves are not replaceable individually. Here's the 6L80 ATSG manual with solenoid info for reference: atoc.ru/uploads/manual/5fb79aebb40df.pdf

[@dannymaldonado8802]

Thank you very much for all the info u sent me. I appreciate it very much. One again thank you.and If I get into a bind hopefully I can write u again.

[@dannymaldonado8802]

One more thing is that the same for a transmission 6180e 6.2 motor on my Cadillac Escalade esv.

[@nickstransmissions]

You're welcome, Danny. Check your glove box for the RPO code list - it will have your transmission's RPO (MYC=6L80, MYD=6L90).

[@CholoInTraining1]

my 4l80e doesnt want to drive over 2k rpm in any single gear while driving, any clues?

[@nickstransmissions]

Hi, no clues. You didnt provide anywhere near enough information so there's a ton of possibilites. If you want to provide more details, i can see about getting you pointed in the right direction. Start with vehicle model/year, codes (if any) length of time this has been going on, recent work on the trans (if any), other symptoms (if any), any diag work or troubleshooting you have already done to date on the problem.

[@charlesedwards7099]

Dude you're awesome that is really cool thank you so much that's an awesome video very good tutorial

[@nickstransmissions]

Thank you for the kind words, Charles!