JustAnotherDude

I am wondering if the behavior of my SH-AWD system is working normally or not. I gut stuck and it didn't act as I thought it would. Here is the situation: I live in Montreal, we just got a massive snowstorm and I got my SH-AWD '12 TL stuck for the first time. I was running late and did a less than ideal job at shoveling my driveway. While backing up, I got it beached.

The rear left wheel did not have a lot of weight on it and was slipping freely. My driveway was already quite icy before the storm, so the slipping wasn't just because the car was beached but also because the surface was very slippery.

The issue I have is that it was the only wheel turning. It was acting as a fully opened diff AWD system. I thought SH-AWD could do a better job at shuffling the power and sending it the other rear wheel or the front. It is normal or not. I ended up shoveling some snow under the rear left part of the car and got the car out quite easily after that.

This is my first post so I hope this is the right place for it.

dopeboy1

hmm I didn't think these things could get stuck. Was under the impression that if one or more wheels starts slipping it will send power to the other wheels.

Just curious, do you have winter tires?

JustAnotherDude

Yes, I do have winter tires. (It's a law here ) And I also never managed to get stuck even if I sometimes put it through some heavy stuff.

Recently, I've had a lot of fun with my TL, turning the traction control off and sliding in the snow (in a very reasonable manner). I fear I may have worn the clutches in the SH system.

Nev05

This might be obvious, but is your SH-AWD light on? Reason why I ask is cause I too like you was having some fun in the snow the other day with the traction off and soon as I completed some satisfying donuts, my check engine light and SH-AWD light came on. After this, my AWD was not activating. I parked it up and then took it back out after 30 minutes and the light was gone.

JustAnotherDude

Nope, no warning lights. I am really wondering about how SH-AWD works. I read this article ( Acura SH-AWD: A Comprehensive Analysis | YouWheel - Your Car Expert ) which does a good job of explaining how sh-awd works, but I still can't figure if the system should be able to act like a locked rear or center diff if one rear wheel is slipping.

Teddybear

Turn off traction control (VSA).
Hope you kept all your TPMS sensors in, because you can't disable VSA if you don't have those installed on our TLs.

andysinnh

I second this reply.

Plus - when that was happening, turn the MID display to the SH-AWD screen and see where it thinks it's sending the power. If everything is going to that one wheel that's free, it would show it there.....

I've gotten stuck before in a Pilot with the VTM-4 AWD system. And while not completely the same as SH-AWD, most of the characteristics are the same. Turning off VSA made the car like it went from "I can't get out" to "Hold my beer, let's get out of here". It was that dramatically different.

good luck - andy

MrHeeltoe

iTrader: (1)

Haven't had personal experience but I can add this... That many torque vectoring and limited slip differential systems do rely on a degree of traction in order to work properly. So because the one wheel was spinning with little or no resistance at all, the effect of differential just went away.

This happened once with my TSX it has a limited slip differential. After I service one of my axles came free from the diff and was spinning inside the housing and my car wouldn't move. I would have expected power to go to the other wheel since it's a limited slip system but I was wrong.

Those systems rely on there being some traction at each wheel in order to know where to send the power.

I know that's a completely different system than what you're dealing with but it may be relevant.

Teddybear

I didn't know that about LSD's. I always thought they had a minimum rotation on each side regardless.
Our SH-AWD system uses clutch packs, so there should still be a minimum power send to all wheels when VSA is turned off. If you turn the wheel with VSA off and hit the gas, it will still send a predetermined amount of power to the outside rear wheel.

I've gone thru a freshly plowed 2' snow banks before. There were large SUV's and pickups that got beached trying to clear the same snow bank. I ended up having to go thru the bank a 2nd time to go around the beached vehicles, and go back thru it a 3rd time to make my off ramp. Below was the result of said snow bank lol

MrHeeltoe

iTrader: (1)

"I've gone thru a freshly plowed 2' snow banks before."

In that case all the wheels are slipping and gripping on and off and traction is moving around so the engine knows how and where to send power all the time. With one wheel completely free-spinning with no traction it is a different story. <<<< Hence the difference between AWD and 4WD! A 4WD car can propel itself with even 2 wheels dangling in the air.

JustAnotherDude

Thank you all for your answers. I did not try to turn VSA off; I thought it would try to block the spinning wheel and help the AWD system send power to the other wheels. I did go to the AWD screen and it said it was sending equal power to all wheels. Maybe the SH-AWD wanted to send equal power everywhere but VSA was messing it up considering the exceptional situation the car was in. It's not an off-road vehicle after all.

I did not think at the time that VSA could actually affect the way SH-AWD operates. Now that I'm thinking about it, I do believe VSA off makes SH-AWD behave the best. When sliding around in the snow, VSA and SH-AWD are more fighting then helping each other.

Anyways, this car is still a beast in the snow and a real joy with VSA off on a slippery road.

Teddybear

That's true, i didn't have a wheel dangling (i dont think).
I'm just basing my experience with test videos like this:

MrHeeltoe

iTrader: (1)

hard to say what happened to in op then I guess. Had to be there maybe.

TLguy2013

I'd say it's a combination of several factors. You say the car was 'beached' which, to me, means the car was up to the underbody in snow/ice/slush. Also, the one tire was spinning while the others were doing nothing (I presume). Plus it sounds like you got stuck at the end of the driveway - maybe after the plough went by?

Like Montreal, in my area of Ontario we've had some miserable weather lately, with a lot of snow + ice + milder temps - then a quick freeze again. There is so much ice under the snow that you really don't know what you're driving through/on. The end of my driveway is a mess because of multiple passes by the plough + slush that's now re-frozen like concrete.

The SH AWD system is great 99% of the time, but is not infallible. Anything can get stuck - especially when you're dealing with snow/ice/loose + deep sand. When a car is beached the amount of traction at the drive wheel(s) is reduced significantly. For example the MDX, with the same system as the TL, will not necessarily get stuck in the same situation, because of the higher ground clearance. In your circumstance I think it was the combination of factors (snow/ice/ground clearance) that created your problem. The one wheel spinning was not abnormal because the system couldn't get traction at any wheel - until you gave it something to grip with the snow you piled under one wheel. The SH AWD system has to have something to give it traction - to at least one wheel. If the other three tires were either on ice and/or had limited contact with the ground (because the car is beached) the one spinning tire makes sense to me.

All of this assumes your front wheels were straight and the ground level - rather than sloped upwards, and your snow tires are in good shape. If not that's an entirely different discussion. I'm pleased you were able to get moving again. Getting stuck 1st thing in the morning makes for a crappy start to your day.

Bonz

Living in the front range of Colorado we had an inordinate amount of notable snowfall on multiple days this winter. Last snow was 10 inches on May 21st. My 2010 TLSHAWD with average Nexen NS5000 tires handles things very well. Our driveway is concrete and steep, it manages to negotiate up most times without sliding backwards. The times it won’t make it must park on the dirt road and shovel the driveway before getting up.

I would rate the snow handling characteristics as very good on the road, and dang good for handling the driveway most times.