Four Wheel Drive

[Auggie]

Well it snowed and I have a steep driveway. As I was coming up the driveway and the front wheels started to spin and a light came on the dash and the light would go out come back on ect, ect. When this happened there was a ratcheting or grinding noise from the back of the car. Sounds real bad. Finley only the front wheels were spinning. I backed down the driveway and got a little run at it and made it into the garage with the same dash light and noise. This doesn't seem normal or is it ?

Auggie

 

[brucelinc]

The noise sounds normal for when the traction control is engaged and working properly. With mine, it will definitely spin one of the rears on snow or ice before the traction control kicks in. Keep in mind that the differentials are "open" so you will not necessarily see all four tires spinning at the same time. My guess is that it is fine and your traction control was what you heard. You can turn it off if you would like to test it.

 

[Auggie]

Boy, I have to tell you that noise is loud and it sound like something is about to hatch. I can't believe they would make something like that but I guess it is what it is. Oh, and how do I turn it off. 2015 SHO.

Auggie

 

[brucelinc]

I don't have an SHO but according to the manual for our 2014 Taurus, you press the stability control button momentarily. Manual says the button is in an access door under the climate controls on the SHO. You should see a message in the info display indicating it is off.

If it is like my MKS and our Taurus, you will not be turning off the stability control. For example, with the traction control off, mine will spin on ice or snow if I give it enough throttle when going straight. However, if I am going around a curve and attempt to break the tires loose, the stability control will kick in even with traction control off.

 

[rubydist]

Auggie, which light was it that came on?

 

[Auggie]

Bruce, when your front wheels start to spin do you have loud banging ect noises when the rear diff engages and disengages? Ruby, I will get back to you on the light. Wife has car and won't be back until Monday.

 

[brucelinc]

Auggie, I wouldn't call it loud banging at all. I would describe the normal operation of traction control as somewhat of a grinding sound along with power loss. It is applying brake to the spinning wheel and cutting power. If you are getting a loud banging, you might have an issue.... Here is what the manual says and I highlighted a couple of things:

 

[Auggie]

This ride is new to us so I wonder if the Traction Control system is only for the front wheel drive. The loud banging noise that I hear is definitely coming from the rear differential area and I mean a real harsh noise. I just can't believe Ford would make something like that? I was told that the car uses front wheel drive and that when the front wheels start to loose traction something sends a signal to the rear wheels for AWD ?

 

[rubydist]

the vehicle is normally biased heavily toward the front wheels, but not 100% from my understanding.

 

[brucelinc]

This ride is new to us so I wonder if the Traction Control system is only for the front wheel drive. The loud banging noise that I hear is definitely coming from the rear differential area and I mean a real harsh noise. I just can't believe Ford would make something like that? I was told that the car uses front wheel drive and that when the front wheels start to loose traction something sends a signal to the rear wheels for AWD ?

You may have an issue, Auggie. The car is under warranty so why not just go for a ride with a Ford tech and demonstrate your concern? If you have snow or ice in your area, you should be able to duplicate the noise and the tech should be able to tell you if it is normal or not. I have owned and had as rentals many different vehicles with traction control and they all make noise when they engage. As I said before, if you are getting a severe banging noise there could possibly be something wrong. I haven't heard of any such issues but it is possible.

For what it is worth, the AWD system is more sophisticated than simply directing torque to the rear when the front wheels slip. Yes, it is basically a FWD vehicle but there are sensors that monitor throttle position, individual wheel speed (so it knows if you are turning or going straight), etc. It is a really seamless system and unless something is wrong, you cannot tell how much power is being applied to which end of the vehicle. For example, WOT will trigger torque to be sent to the rear before the front slips. Applying power while going around curves will also transfer some torque to the rear.

 

[Auggie]

Yes Bruce that's exactly what I am going to do is take a tech for a ride and put this to bed. Thanks.

Auggie

 

[SHOdded]

Make sure they check the RDU and fill level, along with the hubs/bearings in the back. Somewhat common problem areas.

 

[Auggie]

SHO, when I changed oil I looked everything over real good and there were no signs of any leaks what so ever any where and the car only has 21000 miles on the od. It seems like the rear unit is locking then unlocking over and over again. I don't know why something hasn't broken yet. Driveway is covered with ice and snow so every time I go up it I get this real loud bad sounding noise. Do you have any ideas ?

 

[SHOdded]

Problem is there are way too many variables in play under the conditions you are describing. This is why we need the car tricked out with sensors (and/or black box) that dealerships have access to.

What I can definitely say from experience is that it should not be clanging or banging. There will definitely be scritching and scratching noises. But things get complex as wheel weight and response changes due to the dynamic nature of snow. Snow packs into wheels, adding weight. Response changes based on how packed the road surface is. And you have 4 corners to deal with, so you are constantly applying/releasing the brakes. If everything (including the brake calipers) is not working smoothly, there will be sudden and loud noises upon engagement.

When you put on bigger & lighter wheels & wider tires, that does not make for good traction at all. Seen plenty of complaints on the Edge AWD even with the OEM 22" wheels, because they are so open-faced.

Aside from the things I have suggested to check, if you are not running dedicated winter tires, that might be something to look into and see it helps. I don't think it would tho.

 

[Auggie]

Nope, no snow tires so I think I will do what Bruce said and get a Ford tech for a test drive. Thanks

Auggie

 

[mrhighcaliber]

SHO, when I changed oil I looked everything over real good and there were no signs of any leaks what so ever any where and the car only has 21000 miles on the od. It seems like the rear unit is locking then unlocking over and over again. I don't know why something hasn't broken yet. Driveway is covered with ice and snow so every time I go up it I get this real loud bad sounding noise. Do you have any ideas ?

Reproducing this phenomenon for a ford tech is the best course of action at this point. When the computer senses slippage it progressively increases the duty cycle or engagement strength of the clutch packs on the rear diff. If this still isn't enough to prevent excess slippage, the computer will modulate power output and utilize the abs system to control the spinning/slipping wheel(s). Throughout this process any loose/weak link within the drive train or braking system will present itself with the noises that you are describing. Could be as simple as loose driveshaft carrier bolts, coupling bolts, or bushings, or more severe issues like leaking/worn CV joints on the drive shaft, or a failing rdu clutch. Even the brake and suspension components can make noise while this is happening. Depending on the situation the system can and will aggressively lock up the rear and/or engage the brakes and the noise could just be a result the system reacting in what it thinks is an emergency-no traction situation. Bottom line, make ford Get it figured out before the warranty is up. Rdu's are not cheap. Lol

Sent from my Nexus 6 using Tapatalk

 

[Auggie]

Yup, that's what I am going to do and thanks for the info.

Auggie