2003 2500 hd 4wd problems-please help

[yeffaham]

I have a 2003 silverado 2500hd. When I put it in 4 wheel drive the front wheels are not pulling. All the lights on the dash work, you can hear the transfer case and actuators doing something when buttons are pushed. Today while in motion at 35 mph I tried to put it in 4 hi and there was some kind of grinding noise. I have been told that it is the actuator, also have been told that it is the encoder motor. I was told this by non pros.I dont know which one is which and what they do.

[j cAT]

Originally Posted by yeffaham

I have a 2003 silverado 2500hd. When I put it in 4 wheel drive the front wheels are not pulling. All the lights on the dash work, you can hear the transfer case and actuators doing something when buttons are pushed. Today while in motion at 35 mph I tried to put it in 4 hi and there was some kind of grinding noise. I have been told that it is the actuator, also have been told that it is the encoder motor. I was told this by non pros.I dont know which one is which and what they do.

the encoder motor failure is common...the service 4wd lt should come on...with the correct drive train scanner a dtc will lead you to what is defective...usually a bad encoder motor...

these 4wd systems are not to be used on solid dry pavement also the transfercase fluid requires frequent replacing...tracII fluid a blue color...

the encoder motor engages the 4wd....the front gear box actuator locks the front axles together...when you go into auto 4wd the actuator locks the front wheels together..

when a slip is detected in auto 4wd ,, the rear and front axles are then locked together by the encoder motor to get 4wd...

i hope that helps understand what does what..

[yeffaham]

My truck does not have the auto 4wd button, just 2hi, 4hi and 4lo. The transfer case is shifting because when I put in 4lo you can tell the gearing is much lower, like if it had a 2wd low. But the front tires just do nothing.Any more help would be great!!!! Also in 2wd the driveshaft will spin but in 4wd the driveshaft will only spin about 1/8 turn.

[j cAT]

Originally Posted by yeffaham

My truck does not have the auto 4wd button, just 2hi, 4hi and 4lo. The transfer case is shifting because when I put in 4lo you can tell the gearing is much lower, like if it had a 2wd low. But the front tires just do nothing.Any more help would be great!!!! Also in 2wd the driveshaft will spin but in 4wd the driveshaft will only spin about 1/8 turn.

the encoder motor failure is common...the service 4wd lt should come on...with the correct drive train scanner a dtc will lead you to what is defective...usually a bad encoder motor...

[yeffaham]

I dont really want to pay a shop to hook up a scanner if possible. Today I removed the actuator and observed the plunger coming out. Then I lifted the front of the truck up and turned the front wheels, the front driveshaft would also turn. So I am thinking that the transfer case is not locking in, which I think would be the encoder motor like j cAT said. Does this sound right to anybody or is their a way I can check to see if it is the transfer case.If it is the encoder motor are these easy to change?

[j cAT]

Originally Posted by yeffaham

I dont really want to pay a shop to hook up a scanner if possible. Today I removed the actuator and observed the plunger coming out. Then I lifted the front of the truck up and turned the front wheels, the front driveshaft would also turn. So I am thinking that the transfer case is not locking in, which I think would be the encoder motor like j cAT said. Does this sound right to anybody or is their a way I can check to see if it is the transfer case.If it is the encoder motor are these easy to change?

the encoder is not hard to replace..the drive shaft may need to be removed and the wheels need to be free to rotate so that the encoder install will line up to the keyed position. you will need to rotate to line this up ...a couple of connectors and a few mounting bolts.
its about 1.5hrs total ...also you do not have to drain the transfercase..but I would make sure that the blue fluid is not gray looking.

I have seen at 1A auto that they sell for 200.oo and this would be the dorman manufacturer..

[yeffaham]

I read that you can take the encoder motor off and shift the TC manually to seeif the TC is working ok. Has anyone tried this?? Also my truck does not have the auto 4wd button so doesn't that mean I don't have the auto-trac TC. I read in the owners manual that manual TC uses dexron fluid and the auto TC uses the blue fluid which one do I have. Dont mean to sound dumb but I am used to the old school with linkage and hubs.

[j cAT]

Originally Posted by yeffaham

I read that you can take the encoder motor off and shift the TC manually to seeif the TC is working ok. Has anyone tried this?? Also my truck does not have the auto 4wd button so doesn't that mean I don't have the auto-trac TC. I read in the owners manual that manual TC uses dexron fluid and the auto TC uses the blue fluid which one do I have. Dont mean to sound dumb but I am used to the old school with linkage and hubs.

with your vin# in hand call the dealer parts department and ask what transfercase you have and what fluid is required....

drain some fluid what is the color..?

[j cAT]

Originally Posted by j cAT

with your vin# in hand call the dealer parts department and ask what transfercase you have and what fluid is required....

drain some fluid what is the color..?

the manual transfercase NP2 is a lever controlled 4wd....you move a lever...

the automatic transfercase NP8 you push a button....this type uses tracII fluid only available at dealer....

[Bob_La_Londe]

Originally Posted by j cAT

these 4wd systems are not to be used on solid dry pavement also the transfercase fluid requires frequent replacing...tracII fluid a blue color...

How frequent?

[j cAT]

Originally Posted by Bob_La_Londe

How frequent?

this vehicle was not designed to operate in 4wd or auto 4wd on solid dry pavement....this is stated in the owners manual as it WILL rapidly wear the drive train...

also the rotation of tires and the maintaining of tire wear of all 4 tires to match as close as possible will aid in reducing the 4wd failures...

In auto 4wd the front axles are LOCKED together when turning on solid dry pavement you are beating up the front diff..

all these fluids must be checked for level and condition and if this vehicle is used frequently to haul tow it would be wise to replace fluids often..

with my mixed use the fluid appears to need replacing at 30-40,000mi...transfercase...

the front diff was replaced at 5,000mi then 15,000mi then 60,ooomi..then 30-40,ooomi after that point.. the front diff had a gray color to the oil so it was replaced at these mileages , and now it is staying clean..