Transmission kickdown cable question

[gamefreakgc]

The transmission cable is for downshifts during acceleration, what you are referencing from the FSM is for downshifts during deceleration. Still important and yes, it is controlled via the ECU. It's done so subtly though that most people won't even be able to tell when their transmissions shifts while coming to a stop. No one ever has issues with downshifts during deceleration, unless the transmission really is toast.

 

[jhfleet]

The transmission cable is for downshifts during acceleration, what you are referencing from the FSM is for downshifts during deceleration. Still important and yes, it is controlled via the ECU. It's done so subtly though that most people won't even be able to tell when their transmissions shifts while coming to a stop. No one ever has issues with downshifts during deceleration, unless the transmission really is toast.

Okay, I think you're saying all upshifts and all downshifts during deceleration are electronically controlled. But, you're saying forced downshifts during acceleration are hydraulically controlled by line pressure? That may be the case, but it's inconsistent with everything I've read on the subject including Toyota mechanic training publications. The ECT normal/power selector is the only way I've found to change shift points. And, as far as I know, there's no disagreement that all Gen 3s have electronically controlled transmissions. I can't find a reference anywhere suggesting adjusting the transmission cable to change the kickdown point. But, I'll certainly read such a reference with an open mind if you will point one out to me.

 

[gamefreakgc]

Okay, I think you're saying all upshifts and all downshifts during deceleration are electronically controlled. But, you're saying forced downshifts during acceleration are hydraulically controlled by line pressure? That may be the case, but it's inconsistent with everything I've read on the subject including Toyota mechanic training publications. The ECT normal/power selector is the only way I've found to change shift points. And, as far as I know, there's no disagreement that all Gen 3s have electronically controlled transmissions. I can't find a reference anywhere suggesting adjusting the transmission cable to change the kickdown point. But, I'll certainly read such a reference with an open mind if you will point one out to me.

Put a ton of slack in your cable and you'll find out real quick That's how it was when I got my 4Runner.

 

[jhfleet]

Put a ton of slack in your cable and you'll find out real quick That's how it was when I got my 4Runner.

OK, one more observation from Toyota training materials concerning the A340E/F. I've increased my knowledge about ECTs a lot although I did have a basic understanding of what makes them work. It's been nice to have a good-natured disagreement and I appreciate your input even though I disagree with your conclusions.

I'm paraphrasing, but here's essentially what Toyota says about how the A340 E/F transmissions work: All shifts are made by two solenoids that allow or stop fluid flow to the clutches. These solenoids are controlled by the electronic control unit (ECU). The ECU processes signals from a brake pedal sensor, engine temperature sensor, throttle position sensor and the #2 transmission speed sensor. In 4th gear at cruise speed both solenoids are powered off and the torque converter is locked. If the accelerator is pressed enough for a downshift the converter unlocks, the number 2 solenoid is powered on which causes the clutches to do their magic and the transmission will downshift to 3rd gear. The tension setting of the transmission cable has zero, zip, nada to do with any downshift or any upshift. The ECU doesn't monitor line pressure and upshifts and downshifts are not hydraulically controlled as they were decades ago. A mis-adjusted transmission cable will result in out of limit line pressures which can cause a host of problems.

 

[19963.4lsr5]

Not according to the FSM for the 1996 T4R. The A340E/F section of the manual states that the cable is used for setting hydraulic line pressure and gives a procedure on how to set pressure to specs by adjusting the cable while using a pressure gauge. Another paragraph in that section states that transmission shift points are controlled by the #2 transmission speed sensor in conjunction with the signal from the throttle position sensor. Increasing line pressure over specs might have an effect on downshifts, but that's not the purpose of the cable according to the FSM. I'm no transmission expert, but it seems pretty definitive to me.

+100 the A340 is electrically shifted. That's from the TCM. The trans control module has know clue where the TV cable (kick down cable) is. There is zero feed back.

 

[BlackCat914]

The longer it takes to shift the more it slips. Autos need to have quick shifts. There is a distinct difference though between quick and firm and fast and harsh. Fast and harsh can break stuff. Quick and firm will make it last. You should feel the shift and the RPM's should drop instantly but it shouldn't be so hard that it feels like your spine is going to snap. But with a stock valve body you won't have any issues.

Yup, exactly.

 

[SpidermanGeek]

I guess I should look into adjusting mine. My rig shifts so smoothly, I can barely feel the shift changes. Doesn't feel like it slipping though, but could probably benefit from being slightly firmer.

 

[sjwelna]

Just tightening the kick down cable the way I described isn't going to raise line pressure enough to cause problems. People modify their valvebodies to increase pressure even further for higher HP situations (supercharged/etc) by shimming the accumulators and adjusting the pressure regulator for more pressure. See: http://www.lexusclub.co.uk/lsocautoboxmod.pdf

Obviously any mods are done at your own risk, but it's pretty well known that the A340 is a pretty solid transmission. I've had my kickdown cable adjusted that way for at least a couple years now and haven't had a single issue. Shifts are quicker/firmer but not jarring, I'm not worried about stressing any parts of the drivetrain. Yes the TCU is responsible for when the shifts occur. The slightly higher pressure basically just keeps the clutch packs from slipping as much during the shift, resulting in a quicker/firmer shift. Just my .02.

-Steve

 

[jhfleet]

Just tightening the kick down cable the way I described isn't going to raise line pressure enough to cause problems. People modify their valvebodies to increase pressure even further for higher HP situations (supercharged/etc) by shimming the accumulators and adjusting the pressure regulator for more pressure. See: http://www.lexusclub.co.uk/lsocautoboxmod.pdf

Obviously any mods are done at your own risk, but it's pretty well known that the A340 is a pretty solid transmission. I've had my kickdown cable adjusted that way for at least a couple years now and haven't had a single issue. Shifts are quicker/firmer but not jarring, I'm not worried about stressing any parts of the drivetrain. Yes the TCU is responsible for when the shifts occur. The slightly higher pressure basically just keeps the clutch packs from slipping as much during the shift, resulting in a quicker/firmer shift. Just my .02.

-Steve

The way the cable is originally indexed is to take all the slack out of it and add a smidgen of tension and call it good. So, if you're not too far away from that it probably won't hurt. Keep in mind that the A340 ECT shift pattern goes to great lengths to keep shifts soft, even to the extent of reducing ignition timing during shifts to momentarily reduce engine power. My issue is with those who say the timing of shifts is controlled by the cable like it does with non-ECT setups. I also disagree with those who say that increasing transmission fluid pressure will result in lower temperatures. That simply defies physics unless the transmission is on its last legs with slipping clutches that won't fully engage with the recommended pressure.

 

[AntleredRuin]

I know that I'm reviving an old thread, but there are several of these threads hovering around the search engines that really don't seem to be very helpful because, as with most threads....
:worthless

Ok, this really is more about the tranny cable, and not the throttle or cruise control cable, but the same basic principal concerning tightening/loosening applies.

First off, this is NOT a transmission kickdown cable; all it does is change the firmness of the shifts. If you want to shift firmer and more noticeably, then tighten the cable. If you want smoother shifts, then loosen the cable. It feels like it kicks down better because you can REALLY feel it. Play with the cable and you'll see that it shifts in the same place most every time.
If you want to change WHERE you shift, then use the ECT button.

I had search far and wide through the old threads and could not find any post that really spelled out what exactly to look for when tightening the cables. As a result, I SUPER tightened my cable, and it felt like my tranny was going to effing explode. It would slam into each gear with enough force to rattle bones. So I backed it off quite a bit and now it's nice and smooth, but still tight.

So, picture time.

Here is how my Tranny cable WAS. As you Can see by the arrow, there's a bit of slack to it. I'm sure other people's may have more slack than mine did.

As per the instructions on this and other posts, I TIGHTENED it down. Note how far the nuts in the circle moved to the left on the cable. This is TOO TIGHT. Unless you like whiplash at every shift.

This is how it should look when properly tightened. The cable is not perfect (note the hint of slack) but it's not going to flop around and possibly cause your tranny to slip when changing gears either.

Adjusting this cable also affects the firmness of your shifts to Drive, Reverse, Park, etc. Tighter, and you'll lurch into gear. Looser, and it'll be smoother, like a Toyota should be.

Now, you CAN tighten up the engine throttle cable (as you may have noticed in my pictures) because all this does is decrease the amount of play in the gas pedal. You feel like you're taking off faster because your 4Runner is more responsive to your foot. It would actually be the same if you 'floored it' all the time with a loose cable.

I'm not sure, but I believe the same thing with the Cruise Control; it just makes it more responsive.

Well there you go.

 

[alumarine]

Only thing I'd be concerned with doing that is it might hold the shifts to long. Ran into that when I tried it with my dodge.

It doesn't control the shift points, just the line pressure.

 

[slowboy]

shift problems

AntleredRuin...or whomever can help...

My A340H transmission in my 1985 Toyota 4x4 P/U does not seem to downshift at all...I 'can' manually downshift from Drive to 2nd gear and manually back up from 2nd to Drive...there just seems to be no 1st to 2nd, upshift or downshift...I tried adjusting the cable going from throttle body to transmission, but cable didn't seem to tighten or loosen any...do you think a new cable there would maybe help my shifting problem?...

Thank you,
slowboy

 

[pauldub]

slowboy, the cable isn't your problem. It's likely that one of the valve body solenoids is bad. You can check the solenoids with an ohm meter if you have a wiring diagram. The resistance should be around 10-15 ohms IIRC.

 

[BLKTACO]

Reviving this tread. My previous 5VZ with the A340E had the lockdown cable. The shifts were always super soft. Never had a issue with it sale sold at 200k

My new 5VZ and A340E has the electronic throttle body so no lockdown cable. I’ve noticed the shirts are much firmer and much more noticeable. The fluid looked brown but on a paper towel was dark red. I have since done several drain and refills. I believe some of my more “harsh” shifts are also amplified by axel wrap on my Tacoma. Which the weak lady’s are know to do when they wear out.

My question is are the electronic transmissions supposed to be more firm and possibly behave a little differently? Anybody ever have experience with the two side by side?

 

[Outsider1]

Since the 2001, 2002 4 runners don’t have a Kick down cable is there a way to convert it so it takes the kick down cable. I have a transmission that I installed and everything fits except the kick down cable doesn’t have a space on the throttle body

 

[gamefreakgc]

Since the 2001, 2002 4 runners don’t have a Kick down cable is there a way to convert it so it takes the kick down cable. I have a transmission that I installed and everything fits except the kick down cable doesn’t have a space on the throttle body

Does it need it? I ask because I think you are in uncharted territory as I've not heard someone who's tried an older transmission into a newer engine. If it runs and drives, try slowly increasing throttle on the freeway until you are almost near flooring it. If it downshifts to 3rd then you're in luck, you don't need it. If not, well you might be stuck.

The throttle body on your model year is an electronically controlled throttle body and not compatible with older year throttle bodies so that rules out swapping it out. I would recommend not trying to disassemble it as that throttle body is almost as expensive as that transmission you just installed.

 

[brillo_76]

I was wondering how this one was Going to play out as it's a transmission change in the last to years.

I Also don't think a throttle body cable assembly from pre 01 will fit those either...

Does it shift properly without out? If so, just zip tie it out of the way .

I think that's just a kick down cable. For when you mash the throttle it kicks down a gear.

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[19963.4lsr5]

I’m pretty sure the cables only job is the control line pressure.

We have shift solenoids that the ECU fires for gear changes. I don’t think this trans has an internal bypass servos etc to do gear selection separate from the shift solenoids.


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[gamefreakgc]

I’m pretty sure the cables only job is the control line pressure.

We have shift solenoids that the ECU fires for gear changes. I don’t think this trans has an internal bypass servos etc to do gear selection separate from the shift solenoids.


Sent from my iPhone using Tapatalk

Yes, that is its one and only purpose. The problem is in 2001 they did away with it and put some sort of electronically controlled thingamabob in the transmission which I'm guessing his older transmission doesn't have. It may not drive the same because of it, as in never downshift unless he can add in the thingamabob into his older transmission.