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The mkiv Supra Owners Club

The Autobox Modes of Operation


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The MkIV Supra autobox is considered by many to be an excellent auto gearbox, and one of the best most have ever driven. It has an Overdrive button and a MANU (manual mode) button, and these are the source of much confusion and urban mytherry. Here below is the function of these buttons and how the autobox responds, according to years of experience of several owners

 

 

Normal Mode (Overdrive ON, MANU OFF)

 

Selecting L will give you 1st gear only

Selecting 2 will give you 1st and 2nd gear, with normal shift logic applied

Selecting D will give you 1st, 2nd, 3rd, and 4th gear (overdrive), with normal shift logic applied

 

 

MANU Mode (Overdrive ON, MANU ON)

 

Selecting L will give you 1st gear only

Selecting 2 will give you 2nd gear only

Selecting D will give you 2nd and 3rd gears only. The box will attempt to stay in 3rd most of the time, but it is possible to kickdown into 2nd if your speed is below 70-75mph. The box will also select 2nd gear if you come to a crawl/stop, and will reselect 3rd using the normal change logic, but the gear changes will be that bit quicker (see below).

 

Overdrive has no effect in MANU mode, you'll never get beyond 3rd gear unless you hit the redline, at which point it changes up into overdrive to protect the engine and gearbox. If you engage MANU whilst is overdrive then it will not immediately change down, but waits until there is a need to change down following normal change logic. If you are going faster than 3rd gear can deliver then it will never change down until your speed drops to something deliverable by that gear. This stands, in fact, for any manual gear selection - it won't happen unless the resultant gearchange drops the revs within the available rev range. Banging it into L at 100mph will merely result in an electronic sneer from the box. :) (Park and Reverse are different matters...)

 

MANU makes the transitions between gears faster. The ECTS throttle system cuts back on the throttle during gearchanges, and in MANU mode it cuts back less, therefore making the shifts harsher but losing a bit less acceleration during the gearchange.

 

MANU mode does not "hold the gear longer" as it holds the gear indefinitely anyway - it shifts when you make it shift. The exception is when the stick is in D, as described above - the shifting pattern will still follow normal logic, i.e. it depends on throttle position, engine load, and revs as to when it changes gear.

 

 

Overdrive Off Mode

 

Selecting L will give you 1st gear only

Selecting 2 will give you 1st and 2nd gear, with normal shift logic applied

Selecting D will give you 1st, 2nd, and 3rd gear, with normal shift logic applied

 

It will not change gear any faster and will not "stay in gear longer" just because overdrive is off. The autobox will already wind up to the redline if you are at wide open throttle, it knows you want power, that's why it's an 'auto' - you don't need manual intervention from the driver to persuade it to stay in gear.

 

Also of note - the gearbox may come out of MANU mode and overdrive Off mode if the gearbox is risking damage by staying in them (i.e. it's overheating).

 

Thanks to Mawby, Class One and Soop Dogg for their technical input to this :)

 

-Ian

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  • 9 months later...

Have to disagree here both my supra's in manu mode would select 4th gear ie overdrive when you push the o/d button in and out and would lock it in 4th until the revs dropped too low for the engine to sustain itself. My aristo which is setup on a mk4 supra aem with manu mode does exactly the same thing.

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  • 3 weeks later...
Man I do not believe I am saying this but use the search button. Its been covered a million times (thats an exaggeration) Basically it allows you to remove the ignition key in gears other than park on J-spec cars.
It also allows you to move the lever out of Park without putting the key in.
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  • 9 months later...

hello i have tt auto, this part in your thread,

 

OverDrive/OFF

It will not change gear any faster and will not "stay in gear longer" just because overdrive is off. The autobox will already wind up to the redline if you are at wide open throttle, it knows you want power, that's why it's an 'auto' - you don't need manual intervention from the driver to persuade it to stay in gear.

 

so if it does not change any quicker and goes the same then whats the point in having the O/D button

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The OD button will stop the auto box using the 4th gear, which if you're doing some spirited driving through twisty roads is useful as it prevents the auto box constantly changing between 3rd and 4th.

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ok so its there just to give alittle more engine control then, ive tryed it once or twice switching OD off and carnt say ive noticed any difference, was driving normally tho. people on here say if you want to go and give it the beans then pop it out of OD, but as stated in previous thread it goes the same anyway, so its there to provide more engine control/ or engine braking yes

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I nearly always switch the OD off when driving fun roads - it kicks down to second much faster from third than it does from fourth, and just feels much sportier with the revs a little higher (particularly in an NA where the power doesn't really kick in till 5k). Actually I often switch OD off when I'm in a 30/40 zone as well coz it annoys me when it's constantly switching between third and fourth! Probably not the best for petrol usage tho...

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  • 10 months later...
  • 1 month later...

Thanks for this. I had more than a few gripes and worries before going to pick up an automatic tomorrow (never driven one before) but this puts my mind at ease slightly.

 

Am i right in saying for first time driving and getting used to the car, gently, that i should go with over drive on in D untill i get to grips with it ?

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