2002 OB revs when I hit standing water. I suspect that the AWD is not working. No ABS light, so I think the speed sensors are ok. What gives?

it means that your tires are no longer in contact with the actual road surface.. there is a thin film of water between the tire and road - that is what hydroplaning is.

It has nothing to do with AWD, or ABS - it has to do with physically losing contact with the road.

 

How to fix this?

1. SLOW DOWN when approaching standing water.

2. get tires that are better at removing the water from between the treads.

Awd should prevent that wheel from turning faster than the others if it is working properly. I need technical help regaring the AWD system.

Manual or automatic?

 

Take it to some gravel or wet grass or something and see if it kicks in at lower speeds. Or put it on 4 jack stands and put the trans in 1 or R (if auto) and the rear drive should kick in. 

 

GD

Edited October 14, 20178 yr by GeneralDisorder

Awd should prevent that wheel from turning faster than the others if it is working properly. I need technical help regaring the AWD system.

No it won't. Any wheel with no traction to the road surface will turn freely regardless of AWD, 4wd, or ABS operations.

You need new tires andd less foot on the gas pedal, especially when road conditions are poor.

Awd should prevent that wheel from turning faster than the others if it is working properly. I need technical help regaring the AWD system.

 

Yeah.  Based on the lack of understanding of how AWD and Differentials work, I would say you do need technical help on how AWD works.

 

Lightly let up on throttle when this happens, and the wheels will not spin/engine rev. 

Gloyale.. so if it were snow instead of water then it would be OK with you if one wheel continued to spin without the awd directing the power to another wheel?

Gloyale.. so if it were snow instead of water then it would be OK with you if one wheel continued to spin without the awd directing the power to another wheel?

 

That would be a traction control system issue, not an AWD.

 

unless your 02 outback is a VDC model, it will not "redirect" power anywhere.  Power will go out the differentials through the easiest route.  Which will be the wheel with the least traction.

 

When a wheel spins, you need to let off the throttle enough to allow it to regain some friction with the road surface, then apply throttle again. repeat.

Gloyale.. so if it were snow instead of water then it would be OK with you if one wheel continued to spin without the awd directing the power to another wheel?

 

It doesn't work that way. AWD makes the wheel spin. It doesn't make them stop spinning. That would be Traction Control which uses the ABS to slow wheels that are slipping. Your car DOES NOT HAVE TRACTION CONTROL. 

 

Got it?

 

GD

Edited October 14, 20178 yr by GeneralDisorder

No need to be rude GD. I understand now that although most of the torque is sent elsewhere the one wheel can continue spinning under very low friction circumstances. I have 268000 miles on my OB and was afraid that someting was worn out.

No you still don't understand. The torque will ALWAYS go to the wheel with LOWEST friction. The only thing the automatic AWD's can do is send more or less power to the rear depending on traction. They are roughly 90% front wheel drive in D and only send power to the rear If they see a difference between front and rear speed sensors. They can split the power up to 50/50 front and rear. The power will always go to one front, and one rear wheel - whichever has the lowest friction. There is no provision for traction control nor do they have any form of limited slip to equalize the spin between right and left wheels.

 

If you hang one front and one rear wheel (either one) out in space (zero traction) the car cannot move at all. 

 

GD

i never really thought about that that they have drive but not control.

thats very interesting that it is possible to have one wheel or two spinning so high and the others still engaged.

fascinating.

the ideas on this list. 

Has anyone ever had their awd fail due to high milage wear? If so what parts need replaced?

Has anyone ever had their awd fail due to high milage wear? If so what parts need replaced?

 

manual or auto?

 

they have different failure types.  

 

Although it's really uncommon.  they AWD is pretty reliable.

Auto. 268000 miles

So the Automatics use an electronically controlled, multi-plate hydraulic transfer clutch.

 

There are 2 "common" ways it can fail.....although that is uncommon.

 

1:  plates wear out, no friction.  Very little drive to back end and lots of front wheel spin before it kicks in.  Solution, replace the friction discs (or stack another plate set in there

 

2: Transfer (duty C) Solenoid fails, sends full power to rear drive all the time.  Binding when making tight turns on pavement.  Solution, replace solenoid.  related to this is that the transfer drum can get grooves mashed into it from the torque bind, and then even after replacing solenoid, the plates can hang up in the grooves and still bind.  If you find these grooves while replacing solenoid, you must lightly grind them smooth, or replace the transfer drum if they are too bad.

Thanks Gloyale. Haven't experienced any of these symptoms.

Gloyale, I think the plates are failing in our 4EAT, the AWD system is VERY slow to engage, if you get the fronts spinning, you almost have to release the throttle completely to get the Duty C solenoid to kick power rearwards.

 

Have you performed this repair?  Are dealer parts uber expensive?  Should I just start looking for a lower mileage transmission?

Gloyale, I think the plates are failing in our 4EAT, the AWD system is VERY slow to engage, if you get the fronts spinning, you almost have to release the throttle completely to get the Duty C solenoid to kick power rearwards.

 

Have you performed this repair?  Are dealer parts uber expensive?  Should I just start looking for a lower mileage transmission?

in slipping situations, have you tried manually selecting 1st gear? The TCUs programming seems to have varying amounts of torque transfer as a 'base' depending on gear selection.

I haven't tried that since last winter, but I suppose I'll have another opportunity soon.

 

I've been in "D" when it's happened previously.  Most of the time, its at pretty low speeds, like pulling out of a parking lot.  The front wheels will be on snow/ice, rears on wet pavement.  I'll dip into the throttle to pull away and the fronts will just spin and spin, well past the point that I'd expect AWD to kick in, maybe 2.5-3 seconds of front wheel spin, then BAM!!!  RWD engaged.

 

Happened the same way on the freeway once and spun my 90* to the side and almost stuffed it into the guard rail head on...  I'd like to get this fixed for my wife before the weather turns for good.

is there an opportunity to get better tires on the car?

 

anyway, try 1st or second gear next time.

I haven't tried that since last winter, but I suppose I'll have another opportunity soon.

 

I've been in "D" when it's happened previously. Most of the time, its at pretty low speeds, like pulling out of a parking lot. The front wheels will be on snow/ice, rears on wet pavement. I'll dip into the throttle to pull away and the fronts will just spin and spin, well past the point that I'd expect AWD to kick in, maybe 2.5-3 seconds of front wheel spin, then BAM!!! RWD engaged.

 

Happened the same way on the freeway once and spun my 90* to the side and almost stuffed it into the guard rail head on... I'd like to get this fixed for my wife before the weather turns for good.

Yeah sounds like you need new transfer clutch plates. Its usually a good idea to pull the transfer section off the back and pull the drum out and inspect inside the transfer clutch drum for grooves. Depending how bad it is you may need to replace the drum, usually around $500 in parts for the drum and new friction plates.

Edited October 17, 20178 yr by Fairtax4me