All right, in this transmission, we've got three on-off solenoids you've got one right over here
when I hear one right here and they're visibly small little solenoids now if you look back
here there's a great big silver solenoid that's probably I don't know an inch in diameter and two
inches long or so that's a pulse width modulated solenoid so we have to call it a linear solenoid
but it's its pulse width modulated and so these these three solenoids are on-off solenoids this
is a four-speed transmission and so two of those solenoids are going to do the actual shifting of
the four gears think they call them solenoid one and solenoid two some transmissions call
them solenoid a solenoid B it doesn't matter to to move to shift valves to make it upshift and
downshift it only takes two solenoids in this style of a transmission the third solenoid is
a torque converter clutch solenoid to engage the torque converter clutch and then the
the great big pulse width modulated one is the one that controls the actual pressure inside the
transmission the line pressure the line pressure is typically pretty lower to idle maybe 50 psi and
can go as high as maybe 250 psi if you rev it way up at wide-open throttle so it's a variable pulse
width modulated solenoid on these valves though in the valve body let's look at the valve here with
this solenoid it's a shift solenoid right above that valve or above this on/off solenoid
is a valve and I don't know if you see it there's a spring if you can't see it there's a spring up
above it but I'll show you the action of the spring because I can reach in with this pick
there we go so it can go up and it can go down that's that's all that thing
does now I don't know which way is upshifted and which way is downshifted but this solenoid right
here that hooks to that is going to be a solenoid that is just a little tiny thing like this it's
fairly closing in size but if I blow through it that's a normally open solenoid so if this saw
annoyed were plugged in there and there was fluid that came to this point right here and wanted to
push up on that valve and push it up against the spring it wouldn't be able to push how come it can
build pressure the solenoid is open so it's it's it would squirt fluid right out the bottom of that
solenoid as it's mounted here and it wouldn't be able to build up pressure so the spring would keep
the valve pushed down now all it's going to take this only has one wire going to it so the ground
is picked up through the case in the valve body if all we did was apply battery voltage to that which
is we say 12 volts but with the engine running it's 14 13 and 1/2 you apply a voltage to that
it blocks off that passage and now fluid that comes right here is going to build up pressure
and move that valve up now if you look closely at the valve lands the shiny part of the valve
that you see right there is a valve land and then that the recessed part is the valley notice that
this valve land is blocking this fluid passage right here let's say there's fluid that wants to
go from this side over to this side well it that shiny valve land is blocking that from getting
through but look what happens when we lift up on the solenoid it opens it up and lets the fluid
go through now what if that fluid went to one of those Pistons that pushes on the clutch pack
that we've been taken apart all week does that make sense so I've been telling you that the
planetary gear sets are controlled by clutches or bands on those really old older transmissions but
the clutches are controlled by valves in the valve body the spring will typically let's say in this
case I don't know what it is I'd have to look it up if the valve is pushed down with the spring
pushing on it just like it is let's say that's first gear and then if we could turn on that
solenoid and block the hood and force the valve to go up against the spring pressure and Lent
fluid through from one passage to the other then that would send fluid to whatever clutch gives
us second gear and then we've got another there's another shift valve over here I think or maid it's
buried underneath over there it doesn't matter it's going to look just like this it's another
long valve with a spring and then we'll move we'll move it and it will allow us to shift from second
to third gear and then we'll come back to this one we're going to release it and that previous
valve that shifted us into third gear is going to put oil up in another passage that there was no
oil there before and so now when this valve comes down it lets fluid go into whatever clutch orb and
gives us fourth gear so we just toggle back and forth once one solenoid on upshifts us the
lectern up shifts us again we have turned the other one off there's all sorts of on-and-off
combinations I've got all these powerful what I call Richter with range reference charts around
the shop that show the solenoid on/off status of a lot of the transmissions that we've got out
here but that status is also available in service information you can find the solenoid there should
be some sort of table that tells you for a first gear or solenoid one is on solenoid two is off
or whatever it may be so the solenoids when you activate them there should be a click an audible
click and so I'll have my jumper box out we're actually going to do some testing of solenoids
here in just a minute but you you'll be able to hear the solenoid click if it clicks that means
electromagnetically the little plunger that moves up and down inside to block that hole is moving
now you can actually have a solenoid that it's resistance checks fine but it doesn't click it's
no good so you want to saw an ID that clicks you want one that will change its function from being
blocking fluid to letting it through or letting it through to blocking and then we want it to hold
pressure also when it's blocking we don't want it to leak and they can leak also so that's some
of the valves in the valve body some other valves like this one right here these are just simply
pressure regulators now since the oil pressure and a transmission is related to engine rpm remember
where's the pump in a transmission right up front and it's driven off the engine crankshaft so if
you turn a pump slowly to idle and then you turn it more quickly at higher rpm you're going to have
higher volume and usually higher pressure with it well we can't have pressure going all over
the place and precisely control a transmission so there's these pressure regulator valves that fluid
will come to the top of the valve and push down if it pushes down far enough it'll just exhaust
into the case and they have a calibrated spring that it might take 90 psi to push the spring down
enough that it will bleed into the case and that way no matter how high fluid pressure gets I'll
say it gets up to 250 it this spring still opens at 90 and the fluid at the top of that valve will
be 90 psi always unless actual fluid pressure is lower than 90 maybe it's set at 30 whatever it's
just a pressure regulator so we have different pressures that we use throughout the transmission
it's not always the height aligned pressure so some of those valves are pressure regulator valve
some are shifting valve type shift and upshift and downshift is some of them are due to control
the flow of that torque converter clutch that we talked about on the Allison the other day we've
got another valve it's buried up underneath but as we move the gear selector that valve is
called the manual valve we can't see it it's covered up but that manual valve routes fluid
to these valves and solenoids so that they can be turn on and off to control it the upshifting
and downshifting so all of these transmissions I don't care what brand it is even that Honda
automatically shifted manual transmission over there still uses these types of valves and Springs
they might be bigger Longer multiple-piece or whatever they might have for anoints or a whole
bunch bigger then a little tiny one up they might have a whole solenoid pack on those 41TES that we
did remember on the side of the transmission you unbolted that big electrical thing that's clear
full of solenoids that controls that transmission okay let me turn this transmission just a little
bit more and show you a few other things these if you haven't looked at this transmission up to this
point it all of this should look familiar starting back here what's this it's your parking gear so
your parking pawl is going to come in and engage that gear and keep it from rotating and that's
spline right to the output shaft so it stops the drive shaft from turning which stops the ring and
pinion from turning which stops the differential cyclers and pinions from turning which stops the
axle shafts and keeps the vehicle from moving as long as both wheels are on the ground you ever
had the misfortune of jacking up one will the vehicle start to roll with an open differential
yeah okay next to it what's this yeah it's just a clutch pack and notice it's its spline to the case
so what's the job of that clutch pack versus a planetary gearset it's a brake it holds something
from rotating this one to another clutch pack oh if we go back here further can you see this
is a piston right here that's a piston that's the piston seal ring that piston reaches up over the
parking gear and is that's what's going to push on that clutch pack to apply so there's our a
little bit of end play remember you're supposed to have some free play in the clutches all your
transmissions are going to have that so here's another holding clutch it has its own piston
down inside of there and then this would be the equivalent of that input housing and inside that
input housing we've got a couple of other clutch packs third do the rotating of the planetary gears
but right here on this transmission, we have a apart and it's cutaway so it's kind of hard to see
but it's the band this band acts as a brake and there's a nice smooth surface right here that
that band is going to wrap itself around and stop it from rotating and if we follow that it comes
clear over and goes down inside the transmission and actually hooks to a Sun gear so that van stops
a Sun gear that's deep down inside and then this is an old three-speed Toyota transmission that
they threw an overdrive unit in front of so sound familiar now that there's a so there's another
planetary gearset up front so there's two in the back it gave us our three speeds and then there's
one more that they put up front here that's either direct drive for first second third gear or it's
overdrive when we go to fourth gear so forth for fourth gear to happen this transmission actually
has to be in third back here and then it spins spins in an overdrive in the front to spend the
whole rest of the transmission but it's just got another clutch pack and notice it is also
spline to the case so it's a break these style of clutch pack right and then one more thing before
we look at solenoid testing here on the side of the transmission of we've got these Pistons
with Springs below and there's another one over here those are accumulators and you've probably
seen these weird little spring-loaded Pistons throughout the transmission on every transmission
it's set the Allison it doesn't have any the job of an accumulator is to do what? it softens the shift
it affects shift quality think of them as a shock absorber for each shift so know which one
is which but let's say that the fingers right here there we go this one let's say that's for the one
two shift when when that shift valve moves and sends fluid to whatever gives us second gear to
the piston it squishes the clutch back to give a second gear it also sends fluid to the top of this
piston where it's going to push down against that spring and it'll kind of give it a slight delay
in the clutch apply and that delay will be a kind of a cushioning delay as it you're pushing against
the spring so that'll give you a nice soft shift and there's a valve and the valve body called an
accumulator valve that's actually going to control a fluid pressure that's back here with the spring
also and so if we have low fluid pressure then this frame won't be nice and pushing and give us
a soft shift but let's say we're wide open to our on we don't want to soft shift but you can't turn
off the accumulator, the piston is still there the spring still there so what they do is hydrostatic
leave lock it in place they fill this passage full of fluid and block it off and coming out and
that holds the piston of solid and so it is like turning off the accumulator piston but it just
prevents it from moving so then you get a nice solid shift and that fluid pressure is variable so
wide-open throttle it's really hard after all it's somewhere in between and life throttle it shoots
barely any fluid pressure at all every one of these transmissions like I said except the Allison
have those accumulators the Allison doesn't have accumulators in it because it uses those
pulse width modulated solenoids to shift the transmission so besides a solenoid besides having
on/off solenoids it has two pulse-width modulated solenoids and instead of having a high pressure
that needs to be cushioned it very the pressure that actually applies the clutch instead and
that's the next evolutionary step in transmission control Chrysler has the even next evolutionary
step the 545 and I believe the 62TE that we had a part here last week a lot of those are eliminating
the valves in the valve body itself if you think about it if we're using a solenoid to move a valve
to let fluid go through why not get rid of about and just put this on right there let the valve
control the fluid won't through the salon when the solenoids on the flow goes through and applies
the clutch when it's off it doesn't that's pretty simple design but that's how automotive evolution
has been they take something that they haven't read this year modify a little bit to make it
work with the new idea and then keep changing and changing it so this is old-school of all that all
the newer transmissions there's a GM 6T70 over there that's the same way it doesn't have it still
has some valve in the valve body for pressure regulation and manual valve and torque converter
clutch control but for the most part of the valves themselves do the shifting of the transmission