Just purchased a 2008 RX 350 AWD online and was delivered today. Don't have the owners manual yet as the dealer is overnighting the paperwork. I was driving it and was wondering how to engage the AWD. So I searched and found out it's automatic by sensing wheel slippage, right ?
Then I read about engaging and disengaging 4 lock, where are these controls located ??

 

AWD is AWD, there is nothing to engage unlike 4WD systems. As wheel slippage occurs traction is transferred as needed to the other wheels. On the RX there is no center locking differential for you to deal with. So, no controls for that either. In short, you just drive it and it does what it does automatically for you.

You can search the Owner's Manuals online here:

https://secure.drivers.lexus.com/lex...nual-search.do

The Owner's Manual web site is undergoing maintenance at the moment so I cannot look up the AWD information to point you to.

 

This is how Lexus described the system in your RX:

Advanced All-Wheel Drive
The AWD RX 350 model features a viscous limited-slip center differential, which enhances drivability in all types of driving conditions. The full-time AWD system provides a constant 50/50 front-to-rear power split. If slippage occurs, the viscous differential directs torque to the wheels with the most traction.

 

Thank you for the clarification. I drove it yesterday in the snow and it had great traction. I've owned Jeep's and 4 wheel drive trucks, AWD is good just have to get used to it. I'm used to pushing a button or pulling a lever for 4 wheel drive. We'll see how it handles Minnesota winters. Thanks

 

Congrats on the purchase!

Be sure to post pictures, it's required!

EDIT: Are you StevenR? LOL

 

According to the appropriate Lexus factory shop/repair manuals there is NO VC Viscous Clutch in the RX330 or RX350 series. Apparently someone neglected to tell sales and marketing. The RX300 series does have a VC, but for 2001 and forward the fluid was reformulated such that it doesn't stiffen enough to be of any real help.

If you don't have a TC "off" function then you'll be looking for a "how to" soon enough.


TC intervention is used to "enforce" AWD mode by moderately braking the front, PRIMARY, drive wheels once slippage is detected there. The bad news is that simultaneously with that moderate braking the engine will be FULLY dethrottled.

Here's hoping you need really need AWD as the car you bought doesn't have that capability.

You need to look to the 2010 RX350, and after, for a decently functional AWD system. Nothing even close to the SH-AWD system but certainly a step in the "right:" direction.

 

Hey hypervish, yeah it's me. I should be MNSC3 on BITOG but during registration it got mixed up. Still learning stuff about the RX, wish I had the manual, hopefully be here tomorrow. Good to hear from ya

 

I have driven a number of 4WD and AWD vehicles in my lifetime, though my current RX330 is only FWD. Got my start driving in the deep lake effect snows in western PA of that era. Did not really feel the need for AWD as I am here in FL 90% of the time and 10% during the holidays in PA. Have had a chance to drive many a time in 6" plus of fresh snow on unplowed back roads back home in PA in the RX and had no problems. Tires, IMO, make all the difference and my Bridgestone Alenzas have served me well as did the original OE Michelins for the time they were on the vehicle. If I was living in MN like yourself I might consider putting on a set of Nokians even if I had AWD depending on my needs. As you are probably aware, 4WD/AWD cannot make you a better driver nor can it overcome all the elements. Sometimes it is best just to stay off the roads.

Perhaps my favorite 4WD/AWD vehicle was an early Subaru 4WD Wagon. Had the dual-range transmission and a 4-speed stick. Put on a set of all-weather/all-terrain snow tires and left them on year round. Untouched otherwise. Even with those tires it was not too loud for highway use. Looked good with the white wagon wheels and was pretty much unstoppable regardless of the weather or conditions. I have pretty much always owned multiple vehicles even in my youth, so it was not uncommon for us to store our trailer queens in the old coal mines during the winters and drive something else on a daily basis. Having a 4WD vehicle, usually a truck or Jeep, was almost a must to get around and especially during hunting season.

 

Can you prove this, seems outlandish?

..............................

 

I have noticed with my 2008 AWD RX that when I take off in deep snow that's churned up and I loose traction the engine does loose power and I come almost to a complete stop. I really have to watch it when pulling out into traffic when the intersection has the loose deep plowed snow.

 

Yes, as of the RX330 AWD was STRICTLY a TC function, NO VC. The primary drive wheels, front, develops wheelspin/slip, TC activates...which does have the effect of sustaining engine torque and routing more engine torque to the rear. Regrettably this technique can quickly result in overheating of the front brakes, and/or over stressing of the drive train(***) if left unabated so the engine is automatically dethrottled.

Later RXes have a TC off function so the driver can get a feel for the roadbed traction level and feather the throttle accordingly.

2010 and after RX350 uses the Ford Escape type rear drive clutch to implement AWD capability.

*** Example, 99-00 RX300 had a more robust VC which lead to the horrid level of transaxle failures for the 99 and less so for the 00.

 

it's all time AWD

 

I've had no issues ...none . Very impressed with the awd so far. I've been surprised how well mine get around with tires that are 80% gone. (Michelin tour). I live at the bottom of a nice little hill and have no problems . We currently have around 8/9 inches of snow . Granted it's packed now, but it's been normal for me to drive in 4/5 I inches with NO problems . I've owned a Pilot and 2 expeditions and 4 explorers and H2 and others 4 wheel drive cars. I was a little worried when I first bought it but not now. Mine has no issues with the power problem you stated, I have no idea why that would happen.

 

Try going up your hill and gunning it. You will slip for a second and then all your power will disappear.

 

Your 2008 RX350 does have Trac(tion) and Vehicle Stability Control. The defeat button is under the dash near your right knee. A single press turns off the Trac so you can rock out of snow, etc. Press and hold for more than 3 seconds to disable the VSC. This will permit...um...doin' donuts! Both reset to default ON when the RX is shut off and restarted. This will be on pages 169-172 when you get the manual. The console top button for the E(lectronicly) C(ontrolled) T(ransmission) limits torque by starting in 2nd gear and softening shift points to minimize wheel spin. Also defaults off after a restart, check page 122. Happy Motoring!