Explorer 06 XLT Humming Noise underneath only when 4X4 active after Wheel skid.

[EAC]

Hi,
My Explorer XLT with 171000 kms is making a loud humming Noise only when any Wheel skid. The sound is present no matter how long you drive unless you turn the Truck Off and On again, then the Sound disappeared if 4x4 Auto selected. If 4x4 HIGH and 4x4 LOW manually selected, the Noise is present all times. Again the only way the humming sound is not present is if no wheel skid or if is present, turning the Truck Off and On again.
Please, any help on this issue will be very appreciated.
Regards
EAC

 

[Tech By Trade]

Quit driving on pavement with the 4wd on. switch it to auto.

 

[EAC]

In AUTO is how I'm driving all the Time. Like I said, this happens in AUTO or Manual. I tested selecting Manual since started happening and is how I confirmed even in AUTO or Manual happens. She only need a little skid of any Wheel and start noisy. As soon I turn off the Truck and back on even after 2 seconds (I do when I stop at traffic Light or Street Stop) and no noise until Wheel Skid again (some time with Track light activated, some time not).

 

[Tech By Trade]

Sounds like the 4x4 is staying on? Does the light stay on after the skid? If not it doesn't think its in 4x4 anymore. Probably transfer case controller. If it does stay on it could be a number of things. Hubs, tone rings, ect.

 

[EAC]

What Light exactly? the 4x4? i never had that indicator lighting on when this happens, is only the humming noise and if you are asking about the Track Control Indicator, only light up sometime when slip but obviously this is normal when the wheels slip.

 

[Tech By Trade]

Yes, either one. What happens is when it slips it engages the 4x4. Do you by chance have a match set of tires?

 

[EAC]

In fact i have the Rear Right one different , same Brand, Model and Size, only the pattern a little different so i suspect maybe was this the issue and then last summer when i installed the summer set (all same brand, model and pattern and pretty good condition, less than 2000 kms already) I tried and make it to slips on purpose and the same thing happened , so i discarded this wheel as the problem.

 

[thebrakeman]

At first I thought you mean you "discarded the tire", but I think you are saying you are rejecting the idea that the tire/wheel is the problem. Fine.

I think you have 2 problems:
1. When the center-diff is locked (in any mode), it makes a loud humming sound. You should not have a strange noise like that on any surface, as long as you are driving straight. Unless you know how to work on differentials, you should take it to a trusted shop for diagnosis, adjustment, and/or repair. It could be the center diff, front half-shafts, or anything in-between.
2. When in Auto4x4 mode, and slip is detected, it's pushing torque to the front wheels, like it should. Fine. Problem is, it's not disengaging after the slip stops. Most likely, this problem will go away when you address item #1.

So, take it to a shop that has experience diagnosing, rebuilding, and replacing differentials and related drivetrain parts. Tell them your symptoms. In either case, you should not be driving this vehicle while it's making that noise. When the noise is happening, the center diff is locked, and you will do further damage whenever you make a turn. If you must drive it before getting fixed, take it easy, and don't make any wheel slip.

PS - I'm assuming this is a V8 truck. V6 trucks have some amount of torque going to front and rear all the time, even in Auto mode, so you would have the noise all the time. V8 trucks (in Auto mode) have no torque going to the front at all, until rear wheel slip is detected. That's why you don't have the noise until you get some slip.

 

[EAC]

I want to thanks for the inputs on this matter first and sorry for the late replay.
My Truck is V6 and now the question is:
Let says is a mechanical issue as you refers on the Diff but, why when i shut-off the truck and on again the sound is not there anymore? So, correct me if I'm wrong then on this. You says that the Humming Noise is normal when the 4X4 is active as long still engaged but what looks like she still engaged after all with no reason. Could be an electrical issue that is not deactivating the system when there is no reason to be?
Another thing is that as far my Wife recall, the first time this happened was last Winter after she got the Tire damaged driving low on pressure and the Tire got completely unserviceable and then is when the new one came to the game. We tried to remember if this sound happened before that, but almost for sure was after.

 

[thebrakeman]

Hmmm, does not make sense to me, for V6 drivetrain. I thought that some torque was going to the front all the time. Perhaps it's something in the locking mechanism, when the system locks the diff 50/50.

When you shut off the engine, and restart, it must be electrically resetting the 4WD system to Auto mode. For some reason, it's not resetting as it should, while driving. Why not? I don't know.

 

[07EddyB]

If your traction control or 4WD is kicking on then you should get an indicator light on the dash. Are you seeing anything?

 

[EAC]

Nope, no indicator for the 4x4 or Track Control blinking when this is happening.

 

[EAC]

So today i went to Mr Transmission Shop and we went in to the failure with the Diagnostic Tool hooked up when the Noise present. We couldn't get any fault Code neither the Transmission or the Transfer Case. He got the Wheel Speed Sensor speed with the tool but only for the Left Front and Left Rear wheels and compare with the speedometer and they were in the threshold of the +- 1 kms difference. For some reason was unable to get the readings for the Right Front and Rear Right but he think is the Tool set up not properly reading for the truck. He think nothing wrong with the Sensors.

 

[07EddyB]

It might be worth it to drop the front driveshaft and drive it. If the noise remains then it is the transfer case. If not, then it is the drive shaft, the front differential, or a front axle.
As pointed out earlier, being in 4WD will produce more noise. However, it shouldn't stay there once the slip is over.

 

[michael loibl]

I own a 06 V6. At work we have three 05 V6 explorers as light service trucks. None of them light up the 4WD indicator on the instrument panel when the AUTO 4WD locks in, and u can definitely tell it’s engaged.
All four trucks only light it up if u press the 4WD HIGH button.
One thing on my 2006 is that occasionally after the 4WD auto locks in, sometimes it doesn’t disengage right away even if I reach smooth dry road. I can feel the very slight vibration in the steering wheel and a slight hum.
When this happens, I push the 4WD high button and then immediately push the AUTO button. This stops the noise on mine. Simply pushing AUTO doesn’t stop it. See if that works on yours.

 

[EAC]

Thank you Michael for the input. Now that you mentioned that about reseting the System, I'm not sure 100% if today when i went to the Shop and during the Troubleshooting by the Shop Guy while driving, i think i noticed some how one time he did that as you mention and the noise went away. But again and not sure because i did not put attention on that when happened. Definitely I will try tomorrow and confirm.
Thx

 

[EAC]

Hi Michael, so I did it and confirmed that while driving and the noise present ( 4x4 High engaged) depressing the 4x4 High and then 4x4 Auto the noise disappears and in fact you feel how the truck ride smother and no light vibration on gas pedal which is another sign that is present when the 4x4 still engaged. So, definitely is a good alternative to reset the System while driving without stop and turn off the Truck like I was doing when this happened. Now, in my case this happens all the time and no like yours that only sometimes like you mentioned. I’m in the process of finding a good Electrical Diagrams because now i’m almost 100% sure this is an Electrical issue rather than mechanical.
Maybe someone has this Diagrams from the Explorer and would like to share it?
Thx again.

 

[michael loibl]

You also Mentioned something about replacing one of the tires shortly before this problem occurred. Keep in mind that this system is very sensitive to differences in rolling circumference at each wheel position.
Depending on how worn the other 3 tires are relative to the new one, that could be part of the cause. The system may assume the slight difference in wheel speed is slippage and thus engaging the system

 

[07EddyB]

He got the Wheel Speed Sensor speed with the tool but only for the Left Front and Left Rear wheels and compare with the speedometer and they were in the threshold of the +- 1 kms difference. For some reason was unable to get the readings for the Right Front and Rear Right but he think is the Tool set up not properly reading for the truck. He think nothing wrong with the Sensors.

That really doesn't make sense to me. If he could get two of them then it is set up - AFAIK all of the sensors are the same. I'm thinking this may be related to your problem. Have you checked to make sure those sensors are hooked up? It should have thrown a code if they weren't but who knows. I would at least unplug them and check the connection.

 

[EAC]

That's what had been driving me nuts since all this started last winter. Three of the Tires have the same threads worn out (I meant been in the Truck since I bought it in 2012) then i replaced of the 4 originally came with the Truck, one last winter when my Wife drove it flat. That's concerning to Tires and for the sensors, one Hub (Left Front) replaced a moth before of the Tire issue because ABS Fault at Cluster when backing Up. The ABS failure got fixed with the Hub replacement. A moth after the Tire replaced as well. I didn't know before when I replaced, the Sensors on this Trucks has to be good quality because could induce problems with the Transmission and TC, that's what i had been reading in others searching on the Web about the 4x4. So, could be the tires or the Left Front Sensor from where the Noise is coming from (Left Front Wheel, because is not coming from underneath the Driver seat what could probably point to the TC). I know the Wheel hub is not top quality because the Part and Labor were 200 bucks Canadians, so considering 60 or 70 bucks for the Labor, 130 the Hub. Pretty cheap.