| FConte7 |
| Just purchased a 2004 MDX but without an owner's manual. How do you operate the 4WD. It seems as though it can only be used at low speeds (in 1st and 2nd gear). Any help would be appreciated. |
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| JL_SS |
quote:
Originally posted by FConte7
Just purchased a 2004 MDX but without an owner's manual. How do you operate the 4WD. It seems as though it can only be used at low speeds (in 1st and 2nd gear). Any help would be appreciated.
The MDX switches from fwd to 4wd automatically when wheel slip is sensed. Additionally, it starts out in 4wd when accelerating from a stop until 18 mph is reached, then it reverts to fwd if there is no wheel slip sensed. You can lock in the 4wd by pressing the VTM-4 button in 1st/2nd/rev gear, but that is really only necessary if you are stuck. Under normal conditions you just drive it and the MDX will figure out whether it needs to be in fwd or 4wd. |
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| BlackieMDX |
quote:
Originally posted by JL_SS
The MDX switches from fwd to 4wd automatically when wheel slip is sensed. Additionally, it starts out in 4wd when accelerating from a stop until 18 mph is reached, then it reverts to fwd if there is no wheel slip sensed. ...
This isn't completely correct. The 18 mph thing applies to the VTM-4 lock mode only.
The MDX will send more power to the rear when accelerating or when slip is detected AT ANY SPEED; although the amount sent to the rear varies with the rate of acceleration and speed.
When cruising on dry pavement it's essentially in FWD mode. |
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| JL_SS |
quote:
Originally posted by BlackieMDX
This isn't completely correct. The 18 mph thing applies to the VTM-4 lock mode only.
The MDX will send more power to the rear when accelerating or when slip is detected AT ANY SPEED; although the amount sent to the rear varies with the rate of acceleration and speed.
When cruising on dry pavement it's essentially in FWD mode.
My bad. I was remembering incorrectly - the VTM lock starts reducing power to the rear wheels at 6mph until it is 0 at 18 mph. |
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| JL_SS |
| Here is a great link for 1st gen models: VTM-4 |
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| BrianV |
It's also worth noting that operating in VTM-4 is a bad idea unless your stuck. I think it locks the rear differential which means that if you turn, the wheels will still turn at the same speed which causes one wheel to spin; when you turn one wheels turns faster than the other.
VTM-4 is a bail out for getting out of a ditch, mud, or up an icy driveway; it shouldn't be used for regular offroading unless you get stuck or think you might get stuck, and it should be turned off immediately upon clearing the area.
The MDX supposedly tries to detect spin before it happens based on throttle input, etc. This is different than the cheaper system offered on the Honda CRV which ONLY sends power back when it detects slip. However, I find that the MDX isn't as proactive as I wish. My mom's AWD RX330 and a rental Rav4 I had are considerably better. When I put my foot in the MDX in the rain, the front wheels do slip considerably before it hooks up. The Lexus and Rav4 which are faster vehicles don't. All in all it's a good system for snow and occasional mild tempered offroading, but it drives and feels like a FWD car. The Toyota/Lexus system claims it operates in FWD to conserve fuel as well, but it definitely works better to mitigate slip before it happens than the MDX does, but that's not to say that the MDX doesn't get the job done. |
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