Downshifting Curiosity: From Owners Manual

[Montego Murph]

I was reading through the owners manual looking for something, and this particular passage caught my eye. I'm curious if anyone knows why this would be true:

Do not continue hill climbing or hard towing for a long time in the “3”, “2” or “L” position. This may cause severe automatic transmission damage from overheating. To prevent such damage, “4” position should be used in hill climbing or hard towing.​

For years I was always taught the opposite -- that if you're climbing a hill you're supposed to shift into lower gears to protect the transmission from damage, I suppose to keep it from "hunting" and slamming between gears.

I don't have a hydraulic schematic of the transmission so I can't verify, but in L, 2, and 3, the fluid doesn't bypass the cooler -- I would have noticed this when doing an ATF exchange and shifting through the different positions.

Any thoughts?

 

[Inv4drZm]

I think that paragraph is just trying to explain to car idiots to not leave it in high RPM situations for a long period of time. Don't try to use overdrive when towing, dont be in a lower gear than what you need. Not sure they had anything else in mind when they wrote that.

 

[grave]

i constantly shift in my truck. i only use D (5th) on the freeway and use 4th and 3rd to downshift or just to drive, depending on the road i'm on. i can't not. i drove manual for so long that it's impossible for me not to use the engine for braking.

 

[Fern]

Brakes are cheap compared to a transmission, I don't manually downshift unless it is necessary.

 

[Montego Murph]

I think that paragraph is just trying to explain to car idiots to not leave it in high RPM situations for a long period of time. Don't try to use overdrive when towing, dont be in a lower gear than what you need. Not sure they had anything else in mind when they wrote that.

I suppose that makes sense. Sometimes I just overthink things. Near my house there is a fairly steep hill which is the back entrance to my subdivision. It's pretty handy if I come home during school bus time so I don't risk getting caught behind one of them. Anyway, it's posted 25mph, and my truck usually puts itself in 2nd or 3rd for the trip, and I was wondering what the difference was between the ECM vs me selecting that gear range. However I can see what you mean about people not knowing what they're doing.

 

[V8Man]

The Toyota manuals like the service manuals are poorly translated to English and their exact meanings often leave me shaking my head wondering what I just read.
I think they mean don’t over rev the engine and select the higher gear when you can. When towing at highway speeds I often pull it down coming into a hill then upshift when I top it just to the transmission from hunting back and forth.

 

[Terminator03]

The thing that confused me a bit when I first bought it was that my previous SUV tow vehicle was a 2000 V8 Explorer with a factory tow package, and it specifically mentioned that you should use the “OD off” button on the shifter when towing, but the 4Runner manual makes no mention of that, nor does it have a control to lock out the OD (other than manually shifting into a lower gear). I wish it had that because I found it very convenient to use whenever I towed my boat, or other trailer with a heavy load. The 4Runner does tow very well though, and I’ve seen no I’ll effects from just leaving it in “D” all the time. I just let the trans do it’s thing.:shrug:

 

[Bluesky 07]

The thing that confused me a bit when I first bought it was that my previous SUV tow vehicle was a 2000 V8 Explorer with a factory tow package, and it specifically mentioned that you should use the “OD off” button on the shifter when towing, but the 4Runner manual makes no mention of that, nor does it have a control to lock out the OD (other than manually shifting into a lower gear). I wish it had that because I found it very convenient to use whenever I towed my boat, or other trailer with a heavy load. The 4Runner does tow very well though, and I’ve seen no I’ll effects from just leaving it in “D” all the time. I just let the trans do it’s thing.:shrug:

I could’ve sworn I saw something to this effect in the owners manual when I first bought my truck in 2014. I finally ran across it again the other day. It’s a ridiculously inconspicuous note right at the end of the transmission section.

 

[Terminator03]

I could’ve sworn I saw something to this effect in the owners manual when I first bought my truck in 2014. I finally ran across it again the other day. It’s a ridiculously inconspicuous note right at the end of the transmission section.

Hmm... thanks for posting that! I didn’t see that note!

 

[2014 Warthog]

I have a transmission outlet temp monitor running always when I tow and in all cases downshifting LOWERS the transmission oil temp. So I'm not sure what the deal with that warning is.

Also you should always use engine breaking when towing down steep long hills (like coming out of Death Valley) It's not about saving your break wear long term its about keeping your brakes from failing short term!

 

[07V8]

I have a transmission outlet temp monitor running always when I tow and in all cases downshifting LOWERS the transmission oil temp. So I'm not sure what the deal with that warning is.

Also you should always use engine breaking when towing down steep long hills (like coming out of Death Valley) It's not about saving your break wear long term its about keeping your brakes from failing short term!

This. The transmission is designed to assist with engine breaking which in turn is designed to control speed on descents.

 

[Montego Murph]

but the 4Runner...does it have a control to lock out the OD (other than manually shifting into a lower gear).

Yes -- shifting into (4) from (D) is the same as pushing an OD On/Off button.

Overdrive is simply "top gear" (be it fourth or fifth depending on the car.) We shift to the next gear down, while other cars use a button. Just a design thing, much like how we shift between 2/4/4lo with a knob while others have a separate shift lever.

So basically anytime you would want to turn OD off, (while towing on the highway and it keeps hunting between 4 and 5 for example) shift it over to 4!

 

[Terminator03]

Yes -- shifting into (4) from (D) is the same as pushing an OD On/Off button.

Overdrive is simply "top gear" (be it fourth or fifth depending on the car.) We shift to the next gear down, while other cars use a button. Just a design thing, much like how we shift between 2/4/4lo with a knob while others have a separate shift lever.

So basically anytime you would want to turn OD off, (while towing on the highway and it keeps hunting between 4 and 5 for example) shift it over to 4!

Makes sense, thanks

 

[radlynx]

Brakes are cheap compared to a transmission, I don't manually downshift unless it is necessary.

its not a good idea to ride your brakes. downshifting and tapping your brakes occasionally is the way to go.

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