RX450H handling in snow is big problem
04-06-11, 05:38 PM
#1
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RX450H handling in snow is big problem
After driving RX400H for 4 years, I bought RX450H, assuming that it would be equally a joy to drive. However, I had it only a few months when the first snow hit and it resulted in a crash into a guard rail at 15 MPH in a situation where it should have been elementary to control the vehicle. Thank God for the guard rail. The problem is that while the RX400H only tried to charge the batteries when you pushed on the brake, the RX450H tries to charge the batteries whenever you take your foot off of the gas pedal -- the result of this change is software is disastrous in snow conditions. While it is known and documented in the RX manual that anti-lock brakes may not work in snowy / icy conditions, in the RX400H, one only needed to get one's foot off the brake to regain steering control while in the RX450H, the wheels stay locked and without steering control until one pushes the gas pedal, something that is very unnatural when you are headed for a guard rail. Needless to say, I traded it for an RX350.
04-06-11, 06:14 PM
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actually even the RX400h regens the brakes when you let off your foot from the gas. But sorry to hear about the accident. Perhaps it was the new tires, but snowy conditions are hard to underestimate, especially without a full awd system.
04-06-11, 06:50 PM
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mtnhigh, sorry to hear about the accident. I've driven my 450h through two winters now in anywhere from a dusting to several inches of snow up and down hills with turns at varying speeds. I haven't experienced a loss of control like you described. Snow can be fickle especially if there is ice hidden underneath which may have been what you encountered. No car is immune unfortunately. I wish you better luck in the 350.
04-06-11, 08:39 PM
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RX400H regens
Interesting your comment about RX400H regenning -- that's inconsistent with what I saw -- the meter never went negative (i.e. battery charging) on my RX400H until I pushed on the brake pedal. When I bought the RX450H, I was wondering how it managed to produce more power and get better mileage and I discovered how right away when I first drove it and noticed that the needle went negative as soon as I took my foot off the gas. It looked like a brilliant idea until it backfired when I was on ice and the charging of the batteries (and corresponding drag on wheels that were already locked when I braked) meant that I had lost steering control as the wheels never started rotating again). I'm thinking there needs to be a switch that lets you indicate you are in winter conditions thereby making the software work the same as on RX400H.
04-06-11, 08:47 PM
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mtnhigh, sorry to hear about the accident. I've driven my 450h through two winters now in anywhere from a dusting to several inches of snow up and down hills with turns at varying speeds. I haven't experienced a loss of control like you described. Snow can be fickle especially if there is ice hidden underneath which may have been what you encountered. No car is immune unfortunately. I wish you better luck in the 350.
04-07-11, 05:22 AM
#7
I'm not quite sure how to respond to this because I wasn't there, but like others, sorry for your loss.
After reading it twice tho, you referred the system "backfired when I was on ice" and another comment "I'm thinking there needs to be a switch that indicates when you are in winter conditions". Well duh
. You were on ice and that presents a special problem at any speed. And this is just me, but I'd rather look at the window and determine a winter condition than trust a light on the dash.
Now if I misunderstood you I apologize but like the others here have said that have had Gen I or Gen II models as well, this is the way it works and it's working correctly. The driver can't give up responsibility in hazordus conditions because there is traction control installed. Even VDIM that we all love can't save a near 5000lb hunk of steel on ice. The tires don't have cleats.
Just my two bits.
After reading it twice tho, you referred the system "backfired when I was on ice" and another comment "I'm thinking there needs to be a switch that indicates when you are in winter conditions". Well duh
. You were on ice and that presents a special problem at any speed. And this is just me, but I'd rather look at the window and determine a winter condition than trust a light on the dash. Now if I misunderstood you I apologize but like the others here have said that have had Gen I or Gen II models as well, this is the way it works and it's working correctly. The driver can't give up responsibility in hazordus conditions because there is traction control installed. Even VDIM that we all love can't save a near 5000lb hunk of steel on ice. The tires don't have cleats.
Just my two bits.
Interesting your comment about RX400H regenning -- that's inconsistent with what I saw -- the meter never went negative (i.e. battery charging) on my RX400H until I pushed on the brake pedal. When I bought the RX450H, I was wondering how it managed to produce more power and get better mileage and I discovered how right away when I first drove it and noticed that the needle went negative as soon as I took my foot off the gas. It looked like a brilliant idea until it backfired when I was on ice and the charging of the batteries (and corresponding drag on wheels that were already locked when I braked) meant that I had lost steering control as the wheels never started rotating again). I'm thinking there needs to be a switch that lets you indicate you are in winter conditions thereby making the software work the same as on RX400H.
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04-07-11, 12:24 PM
#8
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There is a snow mode on the RX450h. Our's is my wifes car, she drives a school bus and leaves the house at 5:15 evey morning, sometimes in ice, snow and pretty deep snow. Fortunatley no issues to date.
When it snows again next year I will take it out based on the comments here and try to get it to skid, if it does, it's gone. I don't like the car anyway. Loved the older GX we traded in on this thing
When it snows again next year I will take it out based on the comments here and try to get it to skid, if it does, it's gone. I don't like the car anyway. Loved the older GX we traded in on this thing
04-07-11, 03:29 PM
#9
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The RX450H is just as good as my RX300 in snow. I've driven my brother's RX450H numerous times in the snow, and never experienced what you mentioned. How are your tires?
04-07-11, 04:55 PM
#11
The problem is that while the RX400H only tried to charge the batteries when you pushed on the brake, the RX450H tries to charge the batteries whenever you take your foot off of the gas pedal -- the result of this change is software is disastrous in snow conditions. While it is known and documented in the RX manual that anti-lock brakes may not work in snowy / icy conditions, in the RX400H, one only needed to get one's foot off the brake to regain steering control while in the RX450H, the wheels stay locked and without steering control until one pushes the gas pedal, something that is very unnatural when you are headed for a guard rail. Needless to say, I traded it for an RX350.
However, the 400h goes into regenerative mode when you take your foot off the gas (indicated by the green arrows from motors to battery IF you have the NAV display). Secondly, anti-lock brakes will work in snowy/icy conditions...always. What you may find is that it takes longer to stop in snowy/icy conditions IF the ABS activates, however, you will still be able to maintain steering.
Did you notice if the VDIM system activated?
04-07-11, 09:58 PM
#12
executive matchup
driven in the snow with my RX450h going down hill, no problems whatsoever. agree with cruiter, if you are going too fast on ice, nothing can help you from sliding. that's the problem with some suv drivers today - they think they have AWD and are invincible. it's also ironic that most of the accidents you see in the winter are SUVs and trucks with AWD
04-08-11, 02:32 PM
#13
I've only driven one of our RXs in snow a few times so I'm no expert...however, I was told by a friend in North Dakota that they can easily tell from the difference in skid marks in the snow leading to a ditch if it was an AWD vehicle or not: If AWD, the skid marks are shorter...
04-09-11, 07:55 AM
#14
driven in the snow with my RX450h going down hill, no problems whatsoever. agree with cruiter, if you are going too fast on ice, nothing can help you from sliding. that's the problem with some suv drivers today - they think they have AWD and are invincible. it's also ironic that most of the accidents you see in the winter are SUVs and trucks with AWD
I've only owned an RX450 for two winters, which makes me less than an expert. However, I've never noticed my wheels locking up when letting up on the gas pedal. When that happened mtnhigh, that was some slick ice. Inertial is gonna rule in that situation.
I was hoping to get into the online manual to find the reference to ABS not working, but Lexus has just updated the Drivers' page and things must be busy 'cuz everything is slow loading.
