Auto 4WD diff lock?
October 27th, 2015, 7:12 AM
#1
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Auto 4WD diff lock?
First of all, English is not my first (or second) language, especially when it comes to the techical details around cars, so my apologies if I don't get it right, and I hope the meaning gets across anyway.
As winter is approaching, I've started using "Auto 4WD" instead of "2WD".
From my experience with other vehicles, I expected it to kick in the 4WD when needed only. However, it behaves more like a 4WD vehicle with the differential locked at all times. For example, when I make a tight turn (such as while parking) on a non-slippery surface, the front wheels will kind of "skip" or "jump", due to the different rotational speeds required.
Is this to be expected, and should I switch to 2WD when doing tight manouvres, or is something wrong? If something is wrong, is it a "biggie" or is it an easy fix?
As winter is approaching, I've started using "Auto 4WD" instead of "2WD".
From my experience with other vehicles, I expected it to kick in the 4WD when needed only. However, it behaves more like a 4WD vehicle with the differential locked at all times. For example, when I make a tight turn (such as while parking) on a non-slippery surface, the front wheels will kind of "skip" or "jump", due to the different rotational speeds required.
Is this to be expected, and should I switch to 2WD when doing tight manouvres, or is something wrong? If something is wrong, is it a "biggie" or is it an easy fix?
October 27th, 2015, 10:10 AM
#2
Auto
Auto locks the front hubs, but not the center. If the computer senses a speed difference it locks the transfer case. (or maybe it locks the xfer case, but not the front hubs, it's been a while).
Unless you actually have snow on the road, leave it in 2WD.
Unless you actually have snow on the road, leave it in 2WD.
October 27th, 2015, 3:17 PM
#3
This is actually bad/wrong advice. Auto 4WD is designed specifically for variable conditions like wet/dry/snowy roads.
If you are driving on snow-covered streets, you should have it in 4Hi.
When you are in Auto 4WD, the truck should behave just like it's in 2WD. There should not be any binding or scrubbing when you make sharp turns. If this is happening in your truck, then it indicates a problem
When the computer senses the rear wheels slipping, it engages the transfer case and sends power to the front wheels. It will then disengage the transfer case after a short time when there is no more slippage.
From the owners manual:
If you are driving on snow-covered streets, you should have it in 4Hi.
When you are in Auto 4WD, the truck should behave just like it's in 2WD. There should not be any binding or scrubbing when you make sharp turns. If this is happening in your truck, then it indicates a problem
When the computer senses the rear wheels slipping, it engages the transfer case and sends power to the front wheels. It will then disengage the transfer case after a short time when there is no more slippage.
From the owners manual:
AUTO 4WD: This setting is ideal for use when road
conditions are variable. When driving your vehicle in
AUTO 4WD, the front axle is engaged, but the vehicle’s
power is sent only to the rear wheels. When the vehicle
senses a loss of traction, the system will automatically
engage four-wheel drive. Driving in this mode results in
slightly lower fuel economy than 2HI.
conditions are variable. When driving your vehicle in
AUTO 4WD, the front axle is engaged, but the vehicle’s
power is sent only to the rear wheels. When the vehicle
senses a loss of traction, the system will automatically
engage four-wheel drive. Driving in this mode results in
slightly lower fuel economy than 2HI.
Last edited by intheburbs; October 27th, 2015 at 3:21 PM.
October 28th, 2015, 1:51 AM
#5
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I'd like to use 4WD Auto for snow-less winter conditions, since "black ice" (a thin, almost invisible layer of ice on the road) is quite common here.
I have the original tires, so no tire size change.
Could the reason be in the bold text below?
In other words, the front diff is locked, but power is not sent to it?
I have the original tires, so no tire size change.
Could the reason be in the bold text below?
AUTO 4WD: This setting is ideal for use when road
conditions are variable. When driving your vehicle in
AUTO 4WD, the front axle is engaged, but the vehicle’s
power is sent only to the rear wheels. When the vehicle
senses a loss of traction, the system will automatically
engage four-wheel drive. Driving in this mode results in
slightly lower fuel economy than 2HI.
conditions are variable. When driving your vehicle in
AUTO 4WD, the front axle is engaged, but the vehicle’s
power is sent only to the rear wheels. When the vehicle
senses a loss of traction, the system will automatically
engage four-wheel drive. Driving in this mode results in
slightly lower fuel economy than 2HI.
In other words, the front diff is locked, but power is not sent to it?
October 28th, 2015, 5:03 AM
#6
I'd like to use 4WD Auto for snow-less winter conditions, since "black ice" (a thin, almost invisible layer of ice on the road) is quite common here.
I have the original tires, so no tire size change.
Could the reason be in the bold text below?
In other words, the front diff is locked, but power is not sent to it?
I have the original tires, so no tire size change.
Could the reason be in the bold text below?
In other words, the front diff is locked, but power is not sent to it?
But the front hubs are locked, not the differential. The front axle has an open differential. And since the transfer case is not engaged, all four tires can spin separately when in Auto 4WD.
Again, Auto 4WD is supposed to be used in varying conditions. It's like putting the system in standby. If your truck is behaving like it's in 4Hi when it's set to Auto 4WD, then you have a problem with your system.
October 28th, 2015, 7:08 AM
#7
Let me clarify; by "snow", I meant any less than ideal traction material.
I said snow since that seemed to be the material of concern.
With the front hubs locked, you may notice more noise than usual, and more steering force may be required, even if the transfer case isn't locked (engaged). Perhaps the transfer case was locked when you performed this turn. Your fuel economy will also be lower in 4WD Auto. But I'd also rather pay fuel than end up off the road.
My experience is from my 09. My 1995 Tahoe did not have an 'auto' mode. Nor did any of my Jeeps.
When was the last time you changed the front diff fluid?
I changed mine at 100,000 miles and it came out like grey water...
I said snow since that seemed to be the material of concern.
With the front hubs locked, you may notice more noise than usual, and more steering force may be required, even if the transfer case isn't locked (engaged). Perhaps the transfer case was locked when you performed this turn. Your fuel economy will also be lower in 4WD Auto. But I'd also rather pay fuel than end up off the road.
My experience is from my 09. My 1995 Tahoe did not have an 'auto' mode. Nor did any of my Jeeps.
When was the last time you changed the front diff fluid?
I changed mine at 100,000 miles and it came out like grey water...
Last edited by SabrToothSqrl; October 28th, 2015 at 7:33 AM.