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Discussion Starter · #1 ·
I just bought a 2012 RAV4 with the 2.5 and awd. The cruise control works the same as my 2012 Scion XB that I had, uses the same lever assembly, but it works kinda funny when I use the coast feature. If I'm cruising along at say 60mph, and I hold down on the lever to let it coast and slow down to say 50mph, it'll slow down to about 55mph, and then it rapidly slows down, like its applying the brakes. Is this normal? my scion didn't do this, it just gradually slowed down until I released the lever. Is it actually applying the brakes? I don't see how this is possible unless its actually using the abs valve assembly to do this. Thanks
 

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Yes, it is actually applying the brakes after about 4-5 seconds of coasting.

If you do that when it's dark, you'll see the rear door brake lights above the spare tire actually reflect off the spare tire when it applies the brakes.

So the people behind you will think you're applying the brakes yourself, even if you're just "coasting" with the cruise control.

This is normal (3rd Gen, at any rate) RAV4 behavior: http://www.rav4world.com/forums/96-4-3-general/181401-cruise-control-deceleration-brake-lights.html

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It doesn't just happen when you hold the lever down. If you have cruise control engaged, and pick up speed while going down a steep hill, the brakes will also be applied when your speed exceeds the set speed by 10 MPH (a rough estimate).
 
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OK, thanks guys. Feel better knowing it's normal. Can't say I like it though, feels weird and imagine it doesn't help brake life at all

I agree. If using the cruise control and I need to slow rather gradually I usually disengage it by pulling the stalk towards me - don't want to wear the brakes unnecessarily or alarm drivers who are following by having the brake lights come on for no good reason. On downhill grades where slowing is needed I usually downshift, which disengages the cruise control.
 

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When I was at Ranken in the late 70s, an instructor showed us what rod bearings look like when removed from an engine with a clutch that the driver used the clutch and gears to slow the vehicle down, rather than the brakes. Normally the bottom half of the rod bearing is worn more than the top, but the reverse is true when the engine is used to slow the vehicle.
 

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When I was at Ranken in the late 70s, an instructor showed us what rod bearings look like when removed from an engine with a clutch that the driver used the clutch and gears to slow the vehicle down, rather than the brakes. Normally the bottom half of the rod bearing is worn more than the top, but the reverse is true when the engine is used to slow the vehicle.

Interesting - I've lived in hilly and mountainous terrain for much of my life and routinely have used engine compression often with downshifting, to slow my vehicles and haven't had any engine bearing problems. And as a former truck driver, it would be suicide not to downshift and use engine braking on many downgrades and even to slow the vehicle in lower speed situations and those engines generally go for 500,000 to a million miles without having to be opened up and rebuilt.
 

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Discussion Starter · #9 ·
Interesting - I've lived in hilly and mountainous terrain for much of my life and routinely have used engine compression often with downshifting, to slow my vehicles and haven't had any engine bearing problems. And as a former truck driver, it would be suicide not to downshift and use engine braking on many downgrades and even to slow the vehicle in lower speed situations and those engines generally go for 500,000 to a million miles without having to be opened up and rebuilt.
that was my thought as well as I'm a diesel mechanic for a Mack dealer for the last 15yrs. I've had many manual transmission cars, and always tryed to match my revs when down shifting as its generally the clutch that takes the abuse when you down shift as most people do, and maybe your crank thrust bearings if anything as far as the engine internals go. I believe most cars today probably lock the torque converter clutch up anyways under decel, so I would think that would have the same effect as down shifting a manual trans anyways.
 

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that was my thought as well as I'm a diesel mechanic for a Mack dealer for the last 15yrs. I've had many manual transmission cars, and always tryed to match my revs when down shifting as its generally the clutch that takes the abuse when you down shift as most people do, and maybe your crank thrust bearings if anything as far as the engine internals go. I believe most cars today probably lock the torque converter clutch up anyways under decel, so I would think that would have the same effect as down shifting a manual trans anyways.
I'm going to assume you meant cars today un-lock the converter under decel.
:)
 

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that was my thought as well as I'm a diesel mechanic for a Mack dealer for the last 15yrs. I've had many manual transmission cars, and always tryed to match my revs when down shifting as its generally the clutch that takes the abuse when you down shift as most people do, and maybe your crank thrust bearings if anything as far as the engine internals go. I believe most cars today probably lock the torque converter clutch up anyways under decel, so I would think that would have the same effect as down shifting a manual trans anyways.


The instructor was showing the difference between an engine that was coupled to a manual transmission that was used to slow the vehicle and that of an automatic transmission. The wear was similar, but the top rod bearing was worn more on one and the bottom rod bearing was down more on the other.
You are correct about the thrust bearings wearing out faster on a vehicle with a manual transmission. Most if not all lockup torque converters unlock on deceleration.
 

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Most if not all lockup torque converters unlock on deceleration.
My RAV4 definitely does that. When decelerating down an offramp for example, you can feel a "lurch" of acceleration when the TC unlocks.
 
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