This video is part of a five part series on the 4L60E. In this video, I cover the operation of the electrical solenoids and switches and also cover how they control hydraulic operation in the transmission.
Amazing video, was hoping to see something on the TCC side of things. I have an unusual problem, when coming out of lockup the trans cant seem to find 3rd, this is solved by manually shifting into second then back up into 3rd. If I don't manually shift it and let it roll to a stop the transmission will behave normally again
All good info... I'm still looking for the cause of a momentary drop to 30PSI right before the 1-2 shift. Only drops then and all other pressures good and it doesn't drop when starting in manual 2nd. I guessing 1-2 shift valve sticking or broken spring or 1-2 accumulator valve but no issues on 3-4 so maybe not the valve but just the 1-2 spring. 
My 4L60E on my ‘99 Chevy Astro AWD has been acting up intermittently. The B solenoid has been actuating at undesired times. It refused to shift past 2nd and P0758 code was being thrown. With the ignition “off” I removed the transmission-side connector and probed the B wire back towards the ECM and measured about 35 Ohms to ground. All other solenoid lines measured open circuit to ground as I would expect. So either there’s a soft short to ground in the B wire somewhere or there’s something funny in the ECM. Still some work to do.
@@siuautomotive Sure enough, the B solenoid wire was intermittently grounding to the chassis. The sharp edge of the spring clip that holds the ECM had worn through the bottom of the corrugated split conduit on the wiring harness and worn through the B wire’s insulation and some adjacent wires’ insulation. So my “transmission problem” was a wiring problem all along. Live and learn.
I had a rub-through on a 99 safari that drove me nuts years ago! Turned out to be under the ecu where the loom passed the PS line. Damn near rubbed through the line too! @@testmcgee9230
@siuautomotive - Do you have any videos on the wiring outside of the transmission? I just bought a truck with some of the wires tied together and was trying figure why someone would do that.
I'm trying to fix a P2764 low circuit code. 4L60E TRAILBLAZER 2005/ MAN DATE 8/05. All solenoids check/ohm out good. Wires look plug is ok. Valve body issues or bad torque converter? I'm stumped. Shifts perfect just no Lock up.
That code sets when the computer doesn't see the voltage that it's expecting. When the solenoid is commanded "off," the voltage on the wire going to the TCM should be at 12 volts. This is because the solenoid is fed power from a fuse and the ground is provided by the TCM. When the solenoid is off, the transistor in the TCM is open. And since no current is flowing when the TCM has that transistor open, 12 volts will be present on the wire going to the TCM. When the TCM turns the transistor ON, current will flow and voltage will then drop across the solenoid (when turned completely on, that solenoid is modulated). If there is an open in the wiring, connector, or solenoid, the TCM will see "zero" volts when the solenoid is commanded off. It knows that's a problem so it sets the DTC. It'll also set the DTC if the wire between the solenoid and TCM is grounded, but since you say the TCC never engages, it's probably not that. If I were you, I'd monitor the voltage at pin 1 of the TCM. It should be 12 volts when the TCC PWM solenoid is commanded OFF. If you see low voltage, than you have a bad connection or an open somewhere. It's always possible that you have a bad TCM. I do have a video on basic transmission electrical that explains a bit about these solenoids and their control and I give examples.
@@siuautomotive I'll check the harness for voltage etc. I'll let you know and post my finding for others to use in case they have the same issue. Thanks for the reply!!
@@siuautomotive Update: Finally got the P2764 fixed! After dropping the tranny for a Rebuild. While everything looked ok inside just over 100,000 miles no burnt clutches etc...just pistons that looked slightly dry and probably see better days, I replaced everything. Mainly clutches and I also bought a rebuilt torque converter for $140, bearings all checked ok. Valve body seemed ok. Put tranny back in...still was in limp mode! Just had 2nd, 3rd gear. So With everything replaced checked, the only thing i figured it could be was the computer. Wires at the torque converter clutch pressure control solenoid check out ok also. So Figured gotta be the computer! So got one off e-bay programed for a trailblazer, installed it followed the instructions and bam!...started, dropped it in gear and would you know 1st gear!! Then it went to 2, 3rd, 4th and then overdrive (5th). So it was the computer! Someone had worked on it before I got it and shorted wires and the valve body. I had one solenoid that was burnt, I replaced it and never thought anything of it -- that was my sign and i looked over it, A shorted computer. So all is good one year later its finally fixed! (Weird thing is, it actually shifted a few good time when I first got it but one day just stopped so I thought the computer was probably ok). Hopefully someone can use this info to help them out. Man so much research went into this and i was determined to fix it. It runs like new now. So now I have a $2,500 tranny (the cost of a rebuild one) for about $425. That's a good day for me:)
alright so i have a 2011 chevy equinox, recently my transmission oil leaked out it was driving but then out of know where it will not go , it goes into gear but when i push on the pedal it does not go anywhere,
I have a code on 05 lm7 4l60eshift solenoid stuck open what does this mean I can say every time I come to a stop I feel I need to shift to neutral thanks for what you do huge fan
I have a 2009 Hummer h3t, having a trouble with the transmission fuse blowing once the engine and trans is warm, took it to a mechanic they said the short is in the transmission and that shift solenoid A pulled 60 amps while driving. But when stationary both work fine. Any suggestions? I already changed the wiring harness inside the pan and both shift solenoids, along with the TCM and it still blows the fuse (transmission is the only thing on the circuit no o2 sensors or MAF.) like I said it runs fine cold, wondering if any hydraulic problems affect the shift solenoids. It’s also usually burns the fuse when shifting to 2nd but it’s done it in 1st when put in manual. Like I said when cold it shifts perfectly fine.
My guess is you have a short in the harness between the TCM and the trans. You already ruled out the internal harness by changing it. A TCM couldn't cause the problem, because it's on the ground side of the solenoids. You'll probably find something rubbing through your engine/trans harness somewhere causing an intermittent short. Nothing hydraulic can cause a short in your solenoids. When the trans is shifting, it's probably torquing the driveline and causing the wire to touch ground.
This is a very good video. Was wondering. Do you teach people on how to work and rebuild transmissions? If you do can you tell me where I can take your class?
Are you using a commercially available standalone system? If so, I’d suspect there’s instructions. I’ve never installed one, but I would think that they use a throttle position sensor as input to control line pressure solenoid pulse with modulation.
@@siuautomotive No, seen a lot of people using switches to turn solenoids off and on. The problem with that is it goes to full line pressure, is there anyway that I could use something external like a rheostat to control line pressure? And if so where would I hook it up at? There is a guy on Ebay selling controllers for full manual mode, stand alone system pretty cheap,$129.00 but he doesn't talk about line pressure.
My brain hurts, 😂 this video is amazing Although i got some questions, 98 GMC Sonoma 2.2l 4l60e - No MAF (just map) check engine light for TPS cold 1st few miles shift as it should once everything warms up Kicks out of Od to 3rd sometimes back and forth every 5 secs or so, although it would go into OD for just a few secs if manually down shift to 3ed back to Od, 55mph slightly give it a lil more throttle than needed to hold 55mph it would go into OD until throttle lift then rite back to 3rd, and almost feels like slipping, out of frustration and 3 tps later i left TPS unpluged, 4th gear holds just fine (slipping locked converter) feeling gone just slightly hard shift into 2ed, and no throttle down shift, I know this is alot to read but for yourself or anyone with some insight for a possible fix would be very appreciated,
I just had my transmission rebuilt and when i try to manual shift it in 1st or just keep it in 1st to do a burn-out or just drive slow in 1st and then give it full throttle, it shifts to 2nd immediately then shifts back to 1st when i let off the gas. What would cause it to shift from 1st to 2nd under full load immediately then shift back to 1st when i let off the throttle??? This is strange and just puzzling to me!🤯🤯🤯
The current should be more if the valve doesn't move because of the flux field will draw more current in the coil, the same as a starter motor winding will draw more current if the motor is held back from being frozen or siezed.
The current is effected by the pintle movement very slightly, but unlike an electrical motor, there’s no counter electromotive force to speak of. The current flow is really a function of its coil resistance.
Can tire size affect transmission performance. I had 31.5 inch diameter (265) to 32.5 inch diameter (285) will 1 inch diameter have any effect on transmission pcm performance.
It can, but I don't think a 1" change will have too much of an effect. The speedometer will be off and the shift timing will not be based on "real" vehicle speed, since it uses a speed sensor off of the transmission or transfer case. It'll probably be off only 2mph at 60mph. Randy's worldwide has some calculators on their website that might help: www.randysworldwide.com/calculators/tire-height
The max line pressure is determined by the pressure reg spring, afl pressure. And the size of the boost valve. So tuning alone cannot increase max line pressure. You can alter pressures between min and max with tuning by changing your pressure control solenoid amperages and adjusting desired shift times.
@@siuautomotive i have 6.0l 2002 drive by cable tunned MAF deleted My 4l60e has lime pressure 60psi max on all gears and all the ways except R has 85psi 2 n 3 n 4 start to slip from 2000 rpm 1 n R verry gòod
If you unplug the trans connector you can verify that the pump can generate pressure. With the engine running in park and the connector disconnected, you should have 200+psi. If it’s still low, then there’s a problem in the trans. If it’s high, there’s a problem with the tune or computer.
Hi.. I have a problem in my hummer h3 2009..4L60E transmission. When i shift to D, it takes abt 2-3 seconds to engage,i can feel throttle response when i shift but takes time to engage the gear . Reverse is fine..changed pressure solenoid too still no help.. What could be the issue? Please reply me.. Thanks
The only clutch that needs to apply for first is the forward clutch. I wonder if you have a cracked forward accumulator piston since it’s likely made out of plastic. It’s the accumulator piston located in the valve body.
@@siuautomotive i checked the accumulator piston looks good..but i couldn't remove the piston.. And when i shake it gives a metal sound i think it's coz of the small spring but not sure.. I'm thinking to put sonnax pinless piston, what r your thoughts about that?
When you pull that steel plate off, the spring should come out. Then grab the accumulator with a pair of snap ring pliers that expand large enough to grab the inside of the piston and pull out. The aftermarket accumulator work well, but many just toss the plastic one and use an aluminum one.
@@siuautomotive ok I'll remove the accumulator and see.. Mostly I'll go for pinless accumulator.. Hope it'll solve my shift problem🙂.. Because i can feel the throttle response abd rpm change when i switch from N to D.. Thank you do much for your replies.. 👍
