'03 silverado 2500 4 wheel drive not operating properly

I have a '03 2500HD Duramax with 6 speed manual and manual transfer case.

When 4 wheel drive is engaged the front and rear wheels seem to want to turn at different speeds.

On ice/snow the truck is almost impossible to control as the front/rear wheels are causing each other to slip.

On dry pavement the front/rear wheels are fighting eachother so hard they leave rubber on the road. In neutral the truck will bring itself to a halt on significant grade. Wouldn't dare take the truck over 30 MPH. 4X4 also would not disengage without reversing.

how long you owned this ? did you change diff gears ?

same sized tires all 4 ?

Recently acquired. Tires all the same. No knowledge of service work done to differentials. Truck has about 110,000 miles.

Sure sounds like different front and rear gears. That would be the 1st thing to check out.

Recently acquired. Tires all the same. No knowledge of service work done to differentials. Truck has about 110,000 miles.

well that explains it . your gonna have to find out what the front rear diff ratios are . I would bring to an shop that does diff swapping so they can get you going quickly in 4WD... determine what gears are in the vehicle and what the vehicle had when factory built.

With the truck on the hoist it was placed in gear to watch wheel revolutions. Front and back seem to be about the same. Front actuator checks out so at this point the problem seems to be in the transfer case.

With the truck on the hoist it was placed in gear to watch wheel revolutions. Front and back seem to be about the same. Front actuator checks out so at this point the problem seems to be in the transfer case.

who check this ?

normal check is to with engine off in 4wd you count the revs of the drive shaft to the wheel rotations . not that I have had to done this but , with this check , an axle shop will know exactly what gears are installed.

about the same is failure , has to be exactly the same .

With the truck on the hoist it was placed in gear to watch wheel revolutions. Front and back seem to be about the same. Front actuator checks out so at this point the problem seems to be in the transfer case.

Great Job!! Pull the T-Case and open it up, or replace it. Then when you find that doesn't fix your issue, maybe you'll get serious about doing a real check on front & rear ratios.

Finally got to meet up with a friend who has a hoist. With the front driveshaft it took about 3 1/2 turns to make one full revolution of the front wheel and a little more than 4 turns of the rear shaft for one revolution of the back wheel. The front differential looks to be in suspiciously newer condition than other drivetrain parts. My conclusion now is that an incorrect front differential was used to replace the original. Hopefully the transfer case wasn't destroyed as a result of this.

Finally got to meet up with a friend who has a hoist. With the front driveshaft it took about 3 1/2 turns to make one full revolution of the front wheel and a little more than 4 turns of the rear shaft for one revolution of the back wheel. The front differential looks to be in suspiciously newer condition than other drivetrain parts. My conclusion now is that an incorrect front differential was used to replace the original. Hopefully the transfer case wasn't destroyed as a result of this.

now you know what I was saying before. its about rotation of the axle to the wheel. no guess work. the axle shop will tell you exactly whats in there by these rotation ratios. sure the drive train if operated in 4 WD will be worn down much much faster.......if its in 4WD. removing the rear diff cover will reveal damage on inspection. a 2003 4wd 2500 with a 6L engine should have a 3.73 diff .. most not all. so my guess is a 3.42 in the front. should be numbers on the axle for ID. also the RPO codes will tell you what was in the vehicle when OEM factory built or with the VIN # the dealership will be able to tell you . with what you say the rear maybe the 4.10 diff.

I was trusting my friends who had done the original diagnosis for an accurate assessment but after the responses I received on this thread I thought I should find out for myself. I really regret not testing out the 4x4 before I bought the truck. Now I'm stuck with it.

The owner's manual lists all Duramax models as having 3:73 gears but I'm going to find out for sure at this point what I'm working with. It might be awhile as winter is winding down and the need for the 4x4 is not as significant but I'll continue to update this thread as I continue to work on it. I have a Harley that needs some attention so getting that on the road for spring/summer is the current priority.

you will not have any problems if its never used in 4WD. what I would do now is replace the diff and transfer case fluids. drop the rear diff cover inspect clean up the box. with the vehicle driven 20 miles replace the transfer case fluid . should be trac II GM transfer case fluid. transfer case fluid needs 3 QTS. 4.10 gears is a good tow/haul truck. good luck....

I finally got this project done a few weeks ago. A 3:73 differential was the solution. I was surprised to find out the front diff from a 1500 model is interchangeable with a 2500 model. Now I have a good 4:10 front differential to get rid of. I was hoping the salvage yard would trade with me but they weren't interested. Thanks for the advice everyone!