4WD

[duman333]

when starting my truck up tonight i got a service 4wd light. i turned my truck off and then started it again and no light. os then i shut off the truck and started back up and light came on. i got home and shut off the engine and then restarted and no sign of light. has anyone incountered this problem? thanks for any input.
duman333

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2001 chevy dmax/alli cc 4wd ls...

[Mic]

Sounds like you got a faulty switch. Take it to the dealer, IIRC part was #15063844

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[ThumbScott]

I had the same thing happen a few weeks ago. I since then have ran in 4wd a lot due to icy roads and now the problems seems to be gone. No more light.

I had something interesting happen I need help with regarding the 4wd. I was on an icy road and had to back up. I put it in 4wd and was going in reverse, and it seemed like no front spin. Then once I hit it hard it started to move back wards and the patches on the road indicated three of the four tires were spinning????? Shouldn't all four of them been spinning, one of the fronts didn't work? Any advise is appreciated.

This is a four wheeler and it behaves completely different then the six wheeler I had before. The six wheeler was whimpy on ice and snow in 2wd, but once in 6wd it was a monster and ran great. I guess that is why I don't know what to expect from the new truck. Seems like 4wd does not work well? Anyone else feel the same way?

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ThumbScott

2001 GMC 2500HD, SB, Xcab, 4X4, Red, LS.
Pulling Travel Supreme 36' triple axle fifth wheeler with a Reese 16K quik Slide hitch.
Air-lift installed.
http://photos.yahoo.com/duramaxscott

[hoot]

You know how a car only spins one wheel? that's cause of the open differential. With 4x4, you have an open differential in the front, so only one wheel up front is driven.

Now with the locker in the rear (if you have it), you would have 3 wheel drive. To get true four wheel drive you would also need a locker in the front. True four wheel drive is actually very dangerous. You don't have nearly the control as with and open dif up front because at least one tire isn't spinning, it's guiding.

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Mike (dmax) DP Member #2429
2001 2500HD GMC Duramax/Allison Summit White CC/SB Loaded
Amsoil Air Filter, Straight Piped PIC (http://uscom.com/~hoot/cars/duramax/gmc/exhaust/jvn03.jpg)
PS2K Propane, 22 Gal. LP Tank PIC (http://onramp.uscom.com/~hoot/cars/duramax/gmc/propane/bigtank1.jpg)
Allison Deep Pan, Transynd Syn ATF PIC (http://uscom.com/~hoot/cars/duramax/gmc/allison/allis10.jpg)
SPA DG-111 Boost/EGT, Nordskog Digital Fuel Level PIC (http://uscom.com/~hoot/cars/duramax/gmc/allison/allis11.jpg)
VentShades, Husky Mudflaps, 255/85-R16 Dunlop Radial Rover RV's
Kennedy Headlight Booster Kit TRUCK PICTURES CLICK HERE (http://onramp.uscom.com/~hoot/cars/duramax/gmc)
1994 K1500 Blazer 350 Loaded, Flowmaster duals

[NutNbutGMC]

^^........4 X 4? Seems like wishful thinking. 2-axle drive = 3 wheel drive. Hoot, what gives with the GMC designation of "4 X 4?"


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2k2 2500HD Crew-Short-D/A, 2-axle drive.
I drive it, like I stole it.

[hoot]

4x4 sounds good. What does 4x4 mean anyway? 4x4=16 or it sounds like 4 in the front and 4 in the rear?
Ford was using 4x2 for their 2wd trucks for a while. Now that confused me. Just sales labels.

Doesn't Chevy get the 4x4 decals?

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Mike (dmax) DP Member #2429
2001 2500HD GMC Duramax/Allison Summit White CC/SB Loaded
Amsoil Air Filter, Straight Piped PIC (http://uscom.com/~hoot/cars/duramax/gmc/exhaust/jvn03.jpg)
PS2K Propane, 22 Gal. LP Tank PIC (http://onramp.uscom.com/~hoot/cars/duramax/gmc/propane/bigtank1.jpg)
Allison Deep Pan, Transynd Syn ATF PIC (http://uscom.com/~hoot/cars/duramax/gmc/allison/allis10.jpg)
SPA DG-111 Boost/EGT, Nordskog Digital Fuel Level PIC (http://uscom.com/~hoot/cars/duramax/gmc/allison/allis11.jpg)
VentShades, Husky Mudflaps, 255/85-R16 Dunlop Radial Rover RV's
Kennedy Headlight Booster Kit TRUCK PICTURES CLICK HERE (http://onramp.uscom.com/~hoot/cars/duramax/gmc)
1994 K1500 Blazer 350 Loaded, Flowmaster duals

[DSLPOWR]

Dealer replaced actuator and switch panel in dash this week. It fixed the problem with the warning light coming on.

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2002 3500 Duramax/ZF6 speed/4x4/LS Interior/Summit white

2001 2500HD/Alli-Max/4x4/LT Interior/Extended cab/short box/Onyx Black/Graphite leather/295 BFG's/Eagle Alloys/MX7000 lightbar/Lund Deflector/DeeZee Gold series Toolbox/DeeZee Aluminum Tread Mud Guards/DeeZee Aluminum Tread Bed rail protectors/BOSS 9'snowplow/Straight piped/EGT and Boost guage (Pillar mount)

1994 Chevrolet 2500/Silverado/4x4/454/9" Lift/35X12.50 BFG's/15X10 American Racings
http://www.picturetrail.com/gallery/view?username=dslpowr

[sooty]

Interesting !! My truck has true 4 wheel drive. If I am on a gravel road with equal traction on all wheels, they all spin when you punch it. Now if I am on ice with the left side and pavement on the right side and I punch it the front wheel on the left side [the one on the ice ] spins and the one of the right [the one on the pavement] does not spin. Both rear wheels spin as the locker takes over on the rear. That tells me the the front end differential is working like it is supposed to. It has a ring gear and pinon gears. Hum, three wheel drive, I don't think so. Jim

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2001 SILVERADO /2500HD EXT CAB /LWB/ DURAMAX / ALLISON / 4X4 / LT / HUSKY MUD FLAPS /
FIRESTONE AIR BAGS/

[TimT]

I started my truck and the "Service 4WD" came on for about 10 seconds, then off. Called dealer and was advised not to worry unless it came on and stayed on.

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'01 GMC K3500 4x4 CC LB DRW Dmax/Alli Pewter/Graphite Line-X StarBoards B&W gooseneck 80 gallon tank/toolbox Fast Idle switch

[ThumbScott]

sooty,

I am learning here so excuse my lack of knowledge on this issue. I know it will be hard not to make fun of me here.

Are you saying it is ok for just the wheel to spin that is on ice or all four should spin when in 4wd?

My dually all six tires would spin when in 4wd.

I just had an interesting thing happen this weekend. The roads were icy here, (lack of salt, due to high prices, whatever) and when in 4wd I got jerked to the right hard when taking off from a stop. I have to be very careful with my 3 wheeler not to take off fast or I will be in one of our 25 feet deep ditches we have around here.

For real. Should all four spin or is this like traction control? The problem with all four not spinning is all four need to spin when all four are on ice not just three!

Any learning info is appreciated.


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ThumbScott

2001 GMC 2500HD, SB, Xcab, 4X4, Red, LS.
Pulling Travel Supreme 36' triple axle fifth wheeler with a Reese 16K quik Slide hitch.
Air-lift installed.
http://photos.yahoo.com/duramaxscott

[DSLPOWR]

As electricity, power takes the path of least resistance- thus a non-locked-open differential (one wheel on dry pavement, other on ice) the wheel thats on ice will spin and the wheel thats on pavement will not. Then you add a locker, posi, or some device that controlls spinning vs. traction in the differential and both wheels will recive power and the vehicle will move due to the wheel that has the traction. Any four wheel drive truck that has no lockers in the front or rear is basically only two wheel drive on a slippery surface. The are called 4x4's because all of the wheels have the potential to turn under the power of the engine but due to the action of a open differential it's not entirely true. The only reasoning I can come up with that both tires would spin with a non-locked differential would be both tires have equal traction. It would be difficult if not dangerous to drive on pavement with both a front and rear diff locked, it would be impossible to turn. The new all wheel drive system GM has come out with senses wheel speed at all four corners and when one wheel spins out of speed vs. the other side that isn't moving somehow through clutches it will equal speed so the wheel with traction will continue to move the vehicle.
So to sum it all up it IS okay for one tire to spin and the other not.
http://www.plauder-smilies.com/jump.gif


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2002 3500 Duramax/ZF6 speed/4x4/LS Interior/Summit white

2001 2500HD/Alli-Max/4x4/LT Interior/Extended cab/short box/Onyx Black/Graphite leather/295 BFG's/Eagle Alloys/MX7000 lightbar/Lund Deflector/DeeZee Gold series Toolbox/DeeZee Aluminum Tread Mud Guards/DeeZee Aluminum Tread Bed rail protectors/BOSS 9'snowplow/Straight piped/EGT and Boost guage (Pillar mount)

1994 Chevrolet 2500/Silverado/4x4/454/9" Lift/35X12.50 BFG's/15X10 American Racings
http://www.picturetrail.com/gallery/view?username=dslpowr

[This message has been edited by DSLPOWR (edited 01-20-2002).]

[Allison Jettester]

Hoot and Dslpower have the right of it. I have a 77 (since 81) and a 95. Both are designated 4wd and neither have locking or posi differentials. You can only make one wheel spin on either axle. But because the front axle is locked to the rear (via the transfer case and is the reason you don't want to drive very far on dry pavement with it locked), one cannot spin without the other. I don't exactly know why, but the trucks have better traction that way than just a two wheel drive with a locker in the back (I had a 75 D**** w/2wd and posi rear and it wouldn't get out of it's own way in sand and is the reason I will NEVER own another 2wd). I have had my 77 in places where no one thought I would ever make it out of and it never even hesitated a second. If I start spinning in a place where I haven't put it in 4 and then stop, shift into 4, I can just feel the truck sort of hunch down (that is the only way I can describe it) and start pulling like it was on dry pavement. It may have something to do with the geometry of front and rear pulling at exactly the same and one can't spin without the other. So it isn't exactly like a 2wd just because only 2 wheels are driving. I have never owned a 4x4 w/locker. I had thought about putting lockers in the one's I have, but never really needed it, but it should be awesome out in the boonies. By the way, the term 4x4 originated way back when by 4wd enthusiasts started using it as slang and now it seems to be an accepted term by all. It was supposed to mean a 4 wheel truck with 4 wheel drive. Maybe it was used to distinguish them from "4 wheelers", a term the big truckers use on the road when referring to mom or pop in a 4 wheel car, and usually not in a pleasant manor (they just cut them off or something).

It is unbelievable how many people don't realize that most 4x4's only drive two wheels. The reason most trucks in the past didn't usually have posi or lockers in the rear is because old technology rears didn't totally release the wheel when going around a corner and would make one slip (because one is now rotating faster than the other) and would chatter and cause tire wear. This is still the reason you don't find factory lockers in the front. When you turn the wheels, those drive joints go nuts (they don't like it much without a locker and 4w engaged). What Hoot said is another reason why--with both fronts spinning, you have absolutely no control of where the truck is going. You have to be extremely careful in wet or snow if the back locks up as it is. You can swap ends really fast (I've had them try to many, many times with posi's). If you do feel the backend start to brake loose, IMMEDATELY let off the gas (or diesel pedal in this case) and NEVER touch the brakes and lightly steer in the direction it is breaking lose.

I'm trying to be helpful here for the folks new to 4 wheel drive. I hope this doesn't start a discussion like torque an Hp (Oh my GOD no)

Joe



[This message has been edited by Allison Jettester (edited 01-20-2002).]

[sooty]

How about a little differentials 101. The site I am referencing is used for model cars but has a wealth of information in it on differentials on two and four wheel drives for vehicles.
http://www.rctek.com/general/differentials.html
I totally disagree with you guys that only two wheels are driven while in four wheel drive. When I am on a dirt road and gun the truck while in four wheel drive I get spin marks at all four wheels, not just one wheel on each axle. If you understand how a differential works it's easy to understand.
I also, hope this isn't another torque/HP issue. If it is I will not be involved past this post. I alway make sure I have studied the book before makeing posts and giving people the wrong information. Later, Jim

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2001 SILVERADO /2500HD EXT CAB /LWB/ DURAMAX / ALLISON / 4X4 / LT / HUSKY MUD FLAPS /
FIRESTONE AIR BAGS/

[DSLPOWR]

Okay, if this were true those of us that have the G80 rear lockers must have wasted the extra what?- $185 for getting a locking differential that does nothing different than a non optioned rear differential? I also blew $1000 on ARB air lockers (front and rear) for my '94 2500. I must be a complete idiot. http://www.62-65-dieselpage.com/ubb/biggrin.gif http://www.62-65-dieselpage.com/ubb/rolleyes.gif With my '94 I can control the locking mechanism in each of the differential by the flip of a switch. If I were to be in two wheel with the rear unlocked (open) and I were to mash it on pavement only one tire will spin. (One wheel peel) With it locked (both rear tires will turn at equal rates) It will smoke both rears. Now lets try four wheel. If I were to "accelerate hard" without the front locked on soft sand or loose gravel I will get whats called torque steer. Torque steer is where power is being delivered to a steer/drive axle thats open and it begins to to take the path of least resistance and thus affects the steering of the vehicle. Thus of course all four tires are going to spin on a dirt road because of equal traction. Look- what if you were to get one tire off of the ground as many rock crawling Jeeps do. On the opposite side of the axle that the tire in the air is the tire that has has traction...let's say it's on a rock. What (in a open diff) wheel do you think will turn when the axle is supplied power? The one in the air! This is why most avid four wheelers have lockers in both front and rear. It's the same prinicpal on ice, snow, dirt, ashphalt, etc. Remember that the open differential always applies the same torque to both wheels, and the maximum amount of torque is limited to the greatest amount that will not make the wheels slip. It doesn't take much torque to make a tire slip on ice. And when the wheel with good traction is only getting the very small amount of torque that can be applied to the wheel with less traction, your truck isn't going to move very much. Getting back to the situation in which one drive wheel is on the ice and the other one has good traction: With this limited slip differential, even though the wheel on the ice is not able to transmit much torque to the ground, the other wheel (with traction) will still get the torque it needs to move. The torque supplied to the wheel not on the ice is equal to the amount of torque it takes to overpower the clutches. The result is that you can move forward, although still not with the full power of your car. I also check my information for being correct before I post, and besides I work on this kind of stuff for a living (and certified)- I should know! http://www.62-65-dieselpage.com/ubb/biggrin.gif


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2002 3500 Duramax/ZF6 speed/4x4/LS Interior/Summit white

2001 2500HD/Alli-Max/4x4/LT Interior/Extended cab/short box/Onyx Black/Graphite leather/295 BFG's/Eagle Alloys/MX7000 lightbar/Lund Deflector/DeeZee Gold series Toolbox/DeeZee Aluminum Tread Mud Guards/DeeZee Aluminum Tread Bed rail protectors/BOSS 9'snowplow/Straight piped/EGT and Boost guage (Pillar mount)

1994 Chevrolet 2500/Silverado/4x4/454/9" Lift/35X12.50 BFG's/15X10 American Racings
http://www.picturetrail.com/gallery/view?username=dslpowr

[Allison Jettester]

Sooty,

You need to study the webpage you posted a little more. Go down to where it talks about cornering. Under 'Important notes' near the top of the page it states that "The output cups and the sun gears are shown in green as they act as one unit, but the left and right hand sides can act independently".

Then go to the bottom where it says "Cornering Action of an Open Differential". This exact same action will happen when one wheel has more traction than the other (click on 'play' and watch the gears). Just as Dslpwr says, if all wheels have the same (but minimal) traction, they can and sometimes do all spin. Punch it on a paved road in 4wd and I guarantee only one wheel in the front will lay rubber. If you don't have a locking rear, only one of them will spin,

But to absolutely convince yourself. Jack up one side of the truck leaving the one front wheel on the ground and one back one on the ground if you do not have a locking rear, lift both rears if you do. Start the truck and put it in gear and you will notice the truck will not move but the tires in the air will spin (or you can just hand spin one if that would convince you). I've been working on them for about 45 years myself.

Joe

[sooty]

"With 4x4, you have an open differential in the front, so only one wheel up front is driven."
These are the statments that I disagree with.There are several references to this type of operation. The wheel with the least traction will always spin. However on equal traction all of the wheels well spin. You are right that when you talk of torque steer you are shifting the wieght balance and therefore one side has more weight distributed to that side, and as a result the light side will always spin even when the traction surface has equal friction qualities. But to say that only one wheel is driven on an open differential is false. If that were the case then all we need is to power one axle and throw the other axle away . These are simple mechanical principles and don't need a lot of study. I would agree the other information you guys posted is good.

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2001 SILVERADO /2500HD EXT CAB /LWB/ DURAMAX / ALLISON / 4X4 / LT / HUSKY MUD FLAPS /
FIRESTONE AIR BAGS/

[DSLPOWR]

I think we may have had a small misunderstanding. LOL http://www.62-65-dieselpage.com/ubb/biggrin.gif You are correct on the "one wheel drive" statement. I hope I didn't come across as saying that one wheel actually powers the vehicle. I am sorry. http://www.plauder-smilies.com/jump.gif
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2002 3500 Duramax/ZF6 speed/4x4/LS Interior/Summit white

2001 2500HD/Alli-Max/4x4/LT Interior/Extended cab/short box/Onyx Black/Graphite leather/295 BFG's/Eagle Alloys/MX7000 lightbar/Lund Deflector/DeeZee Gold series Toolbox/DeeZee Aluminum Tread Mud Guards/DeeZee Aluminum Tread Bed rail protectors/BOSS 9'snowplow/Straight piped/EGT and Boost guage (Pillar mount)

1994 Chevrolet 2500/Silverado/4x4/Blown-injected 454/9" Lift/35X12.50 BFG's/15X10 American Racings
http://www.picturetrail.com/gallery/view?username=dslpowr


[This message has been edited by DSLPOWR (edited 01-20-2002).]

[sooty]

DSLPOWER, Hey, I do not like confrontations , either. No need to be sorry, I just wanted to be sure of what was being said. Hope to meet someday and swap some real lies. LOL. Jim

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2001 SILVERADO /2500HD EXT CAB /LWB/ DURAMAX / ALLISON / 4X4 / LT / HUSKY MUD FLAPS /
FIRESTONE AIR BAGS/

[bobojay]

To add a little more fuel to the fire... http://www.62-65-dieselpage.com/ubb/smile.gif

Over a period of 30 years, (wow that long), I've owned 12 4x4 vehicles of various brands and configurations. All were the non-viscous coupling type transfer case. In other words gear &/or chain drive. The kind all the HD's have I believe. Not the one that's optional in the 1500's with auto 4wd. That's viscous drive.
Some had rear lockers some not.
One was a 1972 Toyota Land Cruiser with no locker on either end. I got in a mud puddle one day with the left front tire and the right rear tire off the ground. The 2 tires in the air with the least resistence would just spin. No power was sent to the 2 wheels in the mud on the ground. I was stuck big time. Had to use my winch to pull out. This was a good example of how an open non-locker differential(s) 4wd vehicle works when in that kind of situation.
That same vehicle, with equal traction on all 4 corners, such as on dry pavement, would leave 4 short black strips when the clutch was popped in 4wd. But if I was in snow or mud with a varying traction situation, and gunned it, would alternately spin one front and one rear shifting sides as it moved along.
My current 2500HD with a G80 locker in the rear, when in 2 wheel drive will spin both rears on wet pavement pushing itself sideways until I let off the gas. In 4 wheel drive both rears and one front will spin, keeping the truck going straight. The front one that spins will be the one with the least traction, usually the left front,(drivers side), just because of the engine torque causing a weight shift off that side.
I also am surprised at the number of people that don't realize that without lockers at both ends, don't have "true" 4wd.
There is only a couple 4wd vehicles sold in this country that have available front lockers. The Toyota Land Cruiser and Lexus LX470, (clones), I believe and maybe a couple models of Land Rover. Also the ultra expensive Mercedes Gelandewagon ??
Hope this contribution doesn't confuse anyone anymore than already.........

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2001 Chevy 2500HD LS 8.1 Allison Ext. Cab SB 4x4 3.73's Rhino Liner Westin Bars Lucerix's on order Built 5/11/2001 Purchased off lot 11/10/2001 Love it so far

[Turbo Al]

Well I am digging way back (in memory) for this one
1. 99% of 4x4 on road (stock) are not actual four wheel drives.
2. Beveled frount ends (non-locking) will send power to the "non-power wheel" at a ratio of 95 to 1 (if I remember right).
3. If you have a "locker" on the rear and beveled on the frount then it's a 3 wheel drive.
4. If you have a beveled on frount and back it's two wheel drive.
5. If you have a 2wd beveled you have one wheel drive.
Flame away http://www.62-65-dieselpage.com/ubb/biggrin.gif



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Member #750
2001 Ext Cab LB 4x4 Duramax/Allison, Victory Red, K & N
1993 6.5 TD 4x4 reg cab LB, 5 speed
1972 Pontiac Lemans

[Flyboy]

Thanks, Guys. This is great information, especially since the truck I have ordered will be my first 4X4. I started to say four wheel drive, but I guess it's just three wheel drive.

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'93 GMC SLE 6.5TD Banks Power Pack D/A Sle XC/LB 4WD TPW 01-01-02 GOA NRA EAA AOPA AMA VFW Good Sam Cessna 180

[a64pilot]

Hey Al,
I have a C3500 with a locker (G80), so I guess that I am a 4wd when all of those guy's with K2500's are only 3wd. Now I know why a Drooley is better
http://www.plauder-smilies.com/boldblue.gif

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2001 C3500 Charcoal Grey
Putco Boss Boards
Putco Virtual Grille
Stainless Sill Protectors
Stainless Exhaust Extension
SPA DG-111 Boost/Pyrometer
Whistler Radar Detector
600 Watt Inverter
Compaq Lap Top W/Moving Map
250 Watt Texas Star Linear Amplifier
Cobra 29 Classic CB Peaked W/Echo Card
102" Steel Whip
Cross Bed Aluminium Tool Box
Catch All Mats

[sooty]

Well I am digging way back (in memory) for this one
1.100% of 4x4 on road (stock) are actual four wheel drives.
2. Ring Gear and pinon frount ends with spider gears will send power to both front wheels equally and will always allocate the torque equally unless out of balance forces exist.

3. If you have a "locker" on the rear and non locker on the front then it's a 4 wheel drive.
4. If you have a non locker on front and rear it's a 4 wheel drive.
5. If you have a 2wd non locker you have 2 wheel drive.
Flame away


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2001 SILVERADO /2500HD EXT CAB /LWB/ DURAMAX / ALLISON / 4X4 / LT / HUSKY MUD FLAPS /
FIRESTONE AIR BAGS/

[This message has been edited by sooty (edited 01-21-2002).]

[This message has been edited by sooty (edited 01-21-2002).]

[Lone Eagle]

When I am running in 4X4 mode with no wheels spinning all four wheels are driving. Later! Lone Eagle

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2002 2500 HD EC,SB,Back Country Bars, B&W Hitch, Pace-Edwards Roll Top Cover.

[Turbo Al]

A64pilot -- forgot the Dually factor http://www.62-65-dieselpage.com/ubb/biggrin.gif
You guys are killing me esp Sooty http://www.62-65-dieselpage.com/ubb/wink.gif
I have a 3 wheel drive when it's stuck somewhere & my 4 wheel drive is called "Warn Winch", shovel or jack. http://www.62-65-dieselpage.com/ubb/smile.gif

[This message has been edited by Turbo Al (edited 01-24-2002).]

[hoot]

Diesel Jay relayed this info to me...... Thanks Jay

Anyway, you were talking about the convention of 2x4 or 4x4 and what they really describe. It's pretty simple, but a lot of folks don't understand
it.

Here's what it actually denotes:

Number of Drive Positions x Number of Wheel Positions

So, for example, a pickup with 2 axles has (4) wheel positions, no matter if it's a dually or SRW. It just has (4) physical positions, relative to the
vehicle, to place a wheel & tire. So, using that understanding, a 2x4 means 2 of the 4 positions are drive wheels. A 4x4 means all four positions have
drive capabilities.

This applies to any vehicle. A 10-wheel dump or tractor has 6 positions [3 axles x 2 positions per axle]. A "single screw" truck with a "tag" axle
would be a 2x6 -- only 2 wheel positions are "motive" and the second tandem axle is simply weight bearing. A "twin screw" truck is a 4x6 -- both tandems are drive axles, so all 4 tandem wheel positions are motive. Only some utility trucks and military vehicles fall into the 6x6 category, with
the addition of a front drive axle.

Easy enough to understand once you know the convention, but it's not noted
in too many places.

Best Regards,
Jay