Defeating VDIM does what exactly?
04-18-12, 07:20 PM
#1
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Defeating VDIM does what exactly?
What does defeating VDIM mean exactly if it integrates the management of power steering, stability and traction control, ABS, electronic brake distribution and assist? Do certain functions simply shut off completely? or do they act more independently?
04-18-12, 08:43 PM
#3
I don't think it completely shuts down those systems.
I did a midnight traffic circle test a couple of weeks ago. VDIM engaged (ECT/Power on) I could hold a nice line all the way to understeer (!).
VDIM off, I could break the rear end loose, but if I tried to hold it ala Stig, I could feel the engine pull power to bring it back in line.
Might be me, might be my tires (Falken 722). Seemed to de-fuel, just less aggressively. Somewhere between AMGs nanny mode (which is never truly "off") and BMWs trac off (which is for better drivers than I).
I did a midnight traffic circle test a couple of weeks ago. VDIM engaged (ECT/Power on) I could hold a nice line all the way to understeer (!).
VDIM off, I could break the rear end loose, but if I tried to hold it ala Stig, I could feel the engine pull power to bring it back in line.
Might be me, might be my tires (Falken 722). Seemed to de-fuel, just less aggressively. Somewhere between AMGs nanny mode (which is never truly "off") and BMWs trac off (which is for better drivers than I).
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TNTorpedo (09-20-21)
04-19-12, 12:31 AM
#4
VDIM integrates ABS, VSC (w/EPS), TRAC and EBD. Out of those, you can disable VSC and TRAC. ABS and EBD cannot be disabled. Electric power steering is a separate system.
You can turn TRAC off, which will allow you to spin the tires as much as you want in a straight line, but if you start to get sideways, VSC will kick in and put an end to your fun. With TRAC off and VSC off, you can do donuts/slide without any interference from the car, only braking (ABS/EBD) systems are in place, which will not function unless there is braking involved. When VSC is off, EPS interaction is also disabled.
With TRAC and VSC off I have never noticed any interference when sliding around.
Jeff
You can turn TRAC off, which will allow you to spin the tires as much as you want in a straight line, but if you start to get sideways, VSC will kick in and put an end to your fun. With TRAC off and VSC off, you can do donuts/slide without any interference from the car, only braking (ABS/EBD) systems are in place, which will not function unless there is braking involved. When VSC is off, EPS interaction is also disabled.
With TRAC and VSC off I have never noticed any interference when sliding around.
Jeff
Last edited by Jeff Lange; 04-20-12 at 08:54 AM.
04-19-12, 05:10 AM
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Thanks for all the responses!
Last edited by ALLCHILL; 04-19-12 at 05:20 AM.
04-19-12, 08:39 AM
#6
Here's a press release from Toyota where it includes that mention-
http://www.google.com/url?sa=t&rct=j...Ep1gE_k6ChWFIQ
Originally Posted by Toyota
EPS is yet another steering development that contributes to driving feel and
controllability in most Lexus vehicles, the Toyota Prius and Toyota Highlander Hybrid.
Rather than using the purely passive hydraulic assist found in conventional power steering
systems, EPS uses precise electronic assist via the built-in DC motor in the steering gear
housing.
The assist is computer controlled to help provide comfortable and controllable levels
of steering effort in most driving situations. With VDIM interaction, the amount of assist can
be instantly varied for the conditions at hand.
controllability in most Lexus vehicles, the Toyota Prius and Toyota Highlander Hybrid.
Rather than using the purely passive hydraulic assist found in conventional power steering
systems, EPS uses precise electronic assist via the built-in DC motor in the steering gear
housing.
The assist is computer controlled to help provide comfortable and controllable levels
of steering effort in most driving situations. With VDIM interaction, the amount of assist can
be instantly varied for the conditions at hand.
04-19-12, 12:55 PM
#7
VDIM may offer inputs to the EPS that may vary the assist slightly, but the EPS is a separate system, and it is the same computer/system on both the IS250 (without VDIM) and IS250/IS350 (with VDIM).
They are in communication, and VDIM interacts with EPS, but EPS is not a part of VDIM.
Jeff
They are in communication, and VDIM interacts with EPS, but EPS is not a part of VDIM.
Jeff
Last edited by Jeff Lange; 04-19-12 at 02:02 PM.
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04-20-12, 06:12 AM
#8
VDIM may offer inputs to the EPS that may vary the assist slightly, but the EPS is a separate system, and it is the same computer/system on both the IS250 (without VDIM) and IS250/IS350 (with VDIM).
They are in communication, and VDIM interacts with EPS, but EPS is not a part of VDIM.
Jeff
They are in communication, and VDIM interacts with EPS, but EPS is not a part of VDIM.
Jeff
Again from that toyota document-
Originally Posted by Toyota
These proven systems include Vehicle Stability Control (VSC), Traction Control
(TRC), Brake Assist (BA), Anti-Lock Brakes (ABS) and Electronic Throttle Control with
intelligence (ETC-i). In addition, two important technologies are employed: Electric Power
Steering (EPS) and Electronically Controlled Brakes (ECB). VDIM then integrates all of
these elements with powerful proprietary software to help seamlessly manage the total
vehicle dynamic package.
(TRC), Brake Assist (BA), Anti-Lock Brakes (ABS) and Electronic Throttle Control with
intelligence (ETC-i). In addition, two important technologies are employed: Electric Power
Steering (EPS) and Electronically Controlled Brakes (ECB). VDIM then integrates all of
these elements with powerful proprietary software to help seamlessly manage the total
vehicle dynamic package.
Just because a car without VDIM has EPS doesn't mean EPS isn't part of VDIM.
there's tons of cars with ABS that don't have VDIM for example, but even you agree ABS is part of VDIM.
Possible source of your confusion-
First gen VDIM (2004) didn't include the active steering component (though it did still include EPS). Second gen VDIM explicitly added it though in 2005-
http://www.theautochannel.com/news/2...14/125451.html
Originally Posted by Toyota
VDIM with active steering control added
Toyota's first-generation VDIM integrated VSC (Vehicle Stability Control), ABS (Anti-lock Brake System), TRC (Traction Control) and electric power steering. By constantly monitoring driver action and vehicle status, it used integrated control to help stabilize a vehicle before performance limits were breached. It made its debut in July 2004 on the Toyota Crown Majesta.
Adding to this, the new VDIM features an active steering function for optimal control of the front-wheel steering angle through VGRS (Variable Gear Ratio Steering), a new technology that can flexibly vary steering responsiveness. As a result, even during startup or braking when the friction coefficient (slipperiness) of the road surfaces under the right and left wheels differs, the new VDIM prevents the vehicle from going off course by optimally controlling the front-wheel steering angle in conjunction with the brakes, engine and steering torque. In this way, a higher level of preventive safety is achieved, along with ideal vehicle performance.
Last edited by Kurtz; 04-20-12 at 06:23 AM.
04-20-12, 08:46 AM
#9
2IS models do not use VGRS, so we would still have what is considered "1st gen" VDIM.
All that being said, I looked into the 2IS' VDIM setup and it has more EPS interaction than I previously thought, so I concede that EPS is definitely a part of VDIM.
I've edited my previous post.
Jeff
All that being said, I looked into the 2IS' VDIM setup and it has more EPS interaction than I previously thought, so I concede that EPS is definitely a part of VDIM.
I've edited my previous post.
Jeff
Last edited by Jeff Lange; 04-20-12 at 08:54 AM.
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