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...

[@kenvaughn1536]

Thankyou so much for putting this much time and effort into this video breakdown. Its absolutely amazing!!

[@nickstransmissions]

Thanks for the kind words, Ken!

[@kenvaughn1536]

@nickstransmissions your welcome. I have an o4 2500hd with the 4l80e...about 80,000 miles on it. it dropped down to -8⁰ here in ohio couple of days ago. She went into limp mode and blew one of the spliced cooling lines off. I lost 2 qts fluid. Now she's stuck in neutral. I had it towed home. Its supposed to warm up to 30⁰ this weekend. I'm going to tinker with it. Now I know how test everything. I'm hoping it's a bad sensor. Or issue with the filter/fluid. It ran smooth like silk prior. Another issue is may have had is that my battery is toasted. It started the truck that day fine. Even to steer it on the tow truck. But the next day it was dead. Got weird readings from it. 5 yrs old. I'm hoping it had a dead cell, perhaps didn't have enough amps to control the sensors properly. Grabbed a new one. So I'm going put her in and test away. Seriously, thanks again for the effort on this!! I'm hoping it's not roasted 🙏

[@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...

[@nicholascorbin2647]

Rebuilt a 4180e about a month ago using your instructions it was wicked helpful! fast forward a bit and I've got an extremely hard 1-2 shift and 4th - overdrive shift. I checked all of the resistance in the solenoids when I installed them but they were used/unknown parts that came with trans. It's throwing a Gov pressure sensor code, but before i drop the pan and swap it for a new one, does the hard shifting in only those gears seem like a possible symptom from a faulty Gov Press Sensor? Just wanted a sanity check from the master before I get after it. Thanks!

[@nickstransmissions]

Hey Nicholas, sorry to hear...Have you checked your TPS, MAF, Ignition Switch and/or Input Speed Sensor? 4L80Es do not have a governor pressure sensor or transducer (The Dodge A518/618 and 48REs do, however) so perhaps you're referring to the Electronic Pressure Control Solenoid? If the EPC has failed open (meaning it's allowing too much pressure into your apply circuits relative to throttle angle/position) then you're more likely to experience harsh 1-2 and 3-4 upshifts given the efficiency and speed in which those two clutch packs apply relative to the direct clutch. Reply with the actual code you're pulling and we can go from there.

[@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.

[@FkTheGov]

Yeah, I Wasn't Exactly Following That Part Of The Diagnostic Procedure Either. You Can't Just Touch A Probe To A Random Metal Table And The Other End To The Manifold Pressure Switch That Has Absolutely Zero Continuity To The Table And Expect To Get Any Consistent Or Accurate Readings. Unless You Had The Metal Frame Of The Manifold Pressure Switch Grounded To The Table With Alligator Clips, You Were Just Testing An Open Circuit. Plus Your Meter Was On Alternating Current Which Is Not Applicable For Testing Direct Current Components. The Rest Of The Video Was Very Informative Though. Should The Manifold Pressure Switch Be Replaced When The Transmission Is Fully Rebuilt?

[@diycast6914]

Thanks for all your super thorough and detailed videos. I test the continuity like you did and they all checked out...but I couldn't get any voltage reading on A, B, or C no matter how many times I tried. Am I doing something wrong or does it simply need to be replaced? What symptoms can this cause while driving?

[@nickstransmissions]

Thanks for watching, diycast6914...What part specifically are you testing?

[@diycast6914]

@@nickstransmissions i followed the exact procedure I learned from your video. All continuity was present when depressing all 5 switches but when I tested thr A,B,C pins, I got zero voltage no matter how much i tried

[@nickstransmissions]

Ok, your multimeter needs to be set to Ohms, not volts...The only thing you can test that's featured in the video by way of voltage is the speed sensors. Do the same test but with your DVOM set to read in Ohms and you'll get readings that will help you confirm or deny the switch is good.

[@diycast6914]

@@nickstransmissions Okay great thanks for the quick reply! I just got confused cause after you tested the 5 pressure switches in ohms, you tben put your multimeter to volts when testing the A,B, and C Pins on the connector....

[@nickstransmissions]

If I did that, then i had a 12 volt power supply but I filmed that video quite a while ago so don't remember exactly what I did...So defer to the video itself and disregard anything I'm saying here as everything in that video represents how I test all of those electrical/electronic components on those transmissions.

[@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!

[@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.

[@whatever4056]

Actually the trans and converter are working perfectly now, just curious if there is the possibility of damage at some point. It has an aftermarket stall converter and a trans go 2 kit installed

[@nickstransmissions]

Transgo HD2? Oh no....hope that pressure relief mod is not installed...If the converter is working then the likelihood of future damage or wear is no different than any other 4L80E with a working converter...In other words, you should be fine; sounds like the problem may have been in the PCM itself....Also please reply to this comment vs making a new one.

[@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.

[@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?

[@silentbravo]

Thanks, looks like valuable troubleshooting info

[@nickstransmissions]

Thanks, SB!

[@whatever4056]

My 4l80e keeps throwing a p1810 code and when the code is active it will not lock up the converter properly, keeps locking and unlocking on the highway. I replaced all the solenoids and the tfp switch and still keeps throwing the code. When my tuner deleted the code so it can no longer throw the code the trans seems to work fine. Any suggestions and can I just continue to use it with the code deleted from the database?

[@nickstransmissions]

I don't know anything about tuning/programming so I'd ask your tuner if he actually turned off the TCC apply all together and removed the fault detection logic that would otherwise store the DTC and max out the line pressure in response to otherwise protect the transmission and converter from slipping...If he turned off the TCC apply all together, you'll be driving around in 3rd and 4th gear with no TCC lock up and a lot more heat will be generated as that converter keeps slipping vs locking up.

[@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.

[@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.

[@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.

[@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.

[@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...

[@hybridmusclegarage4590]

Awesome as always!!

[@nickstransmissions]

Thanks, man!

[@AvilaBAA]

Mine isn’t throwing any codes. It just goes straight to second and only has second and reverse. I’ve swapped my front wheel speed sensors, my maf sensor, and changed my internal wiring harness.

[@nickstransmissions]

There's still a short somewhere either in the transmission or external wiring harness that's putting the transmission into limp mode...These older units may or may not throw a DTC for electrical issues...most of the time they do but occasionally they dont.

[@AvilaBAA]

@ how would I check it? With a voltage tester on the pins in the harness?

[@nickstransmissions]

Did you watch this video? If not, give it a view - it lays out the multimeter testing for you step by step. Shows testing the harness, each solenoid and the speed sensors. You would apply the same techniques to your other components such as your ignition switch, MAF, TPS, etc... Also, make sure you used OEM components...I can't tell you how many times I and others have had problems with aftermarket electronic/electrical components from chain auto parts stores, Rock Auto off-brand and other similar places.

[@AvilaBAA]

@@nickstransmissions yea I watched just wasn’t sure if you meant to do that same thing. I’ll have to test it all and see what’s going on. Maybe I missed it but how do I just test the 12v pin to see if it has all 12 volts?

[@nickstransmissions]

Gotcha, thank you for watching. Test the wiring harness leading to the transmission for 5v reference and 12 volt power. Also check the PCM itself as they can go bad also - been seeing more customers whose vehicles' pcms are failing...

[@chuck3441]

Great job

[@nickstransmissions]

Thank you, Chuck. Appreciate the kind words.

[@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?

[@FarmRoadBilt]

@@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).