02 4wd issues

Dixon700 · January 21, 2016

Hello all im new here. I just bought an 02 sierra 2500hd crew cab long bed. The day I brought it home it seemed like the 4wd drive worked when I was driving on gravel, but today on ice I found that the front definitely doesn't spin. I have no service 4wd lights or anything and you can hear actuators moving and the light goes from 2wd to 4hi and 4 lo. The front diff actuator seems to be working though. I jacked up the front end and with it in 2wd I could spin either front tire and the front driveshaft wouldn't turn. I put it in 4hi or lo and then the front driveshaft turned with the front tires, so it's like the transfer case isn't engaging in 4wd. Because with the rear wheels on fhe ground and beinf in park the front shaft shouldnt turn unless something is broke inside or fhe t-case isnt shifting. Also there are no weird noises while driving. Is there any tests I can do to rule out mechanically failure. I can and have rebuilt transfer cases I just don't want to get into that right now. I have auto enginuity and haven't checked codes yet. Let me know 8f there is some ways to rule out eletronic components so I don't have to tear apart the t-case to find out.

Thanks

Dixon700 · January 22, 2016

NO one have the diagnostic steps for troubleshooting transfer case issues?

00Silverado4x4 · January 22, 2016

Jack up the entire truck and try it in all positions again. Need to find out exactly what is or isn't working. Sounds like the front diff and doing it's job but yes, the transfer case may not be sending power out to the front driveshaft.

Dixon700 · January 23, 2016

Something came apart in the transfer case. Looks like lack of maintenance. The tiny bit of fluid I got out was black as coal and there was bunks of metal in it. I ordered chain, sonnax pump plate, pump, filter, all seals and bearings, and synchro rings. Man these np 263hd are expensive. My np 271d in my dodge I replaced everything but the shift forks for $440 I have more than that into the parts I bought for this np 263hd.

Dixon700 · January 29, 2016

There is a pinhole in the bottom of my case from pump rub. Can these magnesium cases be brazed? If not has jb weld been used successfully? If not I'll either get a new rear case or someone to weld and machine it. Now to another problem i ordered parts for a np 263hd like a hv-069 chain which is wrong. My chain is 84 pins 2 blue links and looks to be a hv-074 Which is for the np 261xhd and 263xhd. Which I thought was only behind the Alison which I thought was never behind the 6.0. Do I have a 4l80e like I thought? Also I think something is messed up with the shift encoder motor. I used a Cresent wrench and put it in 4hi and lo and the front output is turning normally. The only thing I really seen worn in there so far is the fork inserts especially the mode forks. Everything else seems ok and are still wet nothing looks to of got hot enough to start bluing.

The old chain is stretched a bit though.

00Silverado4x4 · February 1, 2016

Honestly for all the work that would need to be done, I'd pull the transfer case and get a new/rebuilt case. The pump rub issue is an internal problem. Until that pump retaining ring issue is fixed, no "repair" will work for very long. When I bought my truck, my case was in the same condition, pump rub, fluid burnt, chain was so stretched that it was actually hopping teeth when in 4x4. I didn't even try to have it fixed, just found a reserviced case to replace it.

Dixon700 · March 5, 2016

Got transfer case fully rebuilt. Replaced all if the bearings, seals, forks, and range hub also. Epoxied all of the worn spots from the pump rub and installed a sonnax pump plate. I have it all back together and the 4wd still doesn't work and I know it's not the front axle actuator. Is there any way to narrow down if it's the shift encoder motor assembly or the switch panel? I hit 4wd and the 4hi light flashes then the 2wd flashes then stays solid.

Dixon700 · April 24, 2016

Found I set the bearing for the main shaft in a tad too deep and didn't have the mode synchro set up correctly. watching some YouTube and using the ol noggin figured it out and now it works well.

lmh64 · December 17, 2017

Hello. I am a new owner of a 2001 2500HD. I'm reading all these old posts to learn more about my truck.

Congratulations for your perseverance. You analyzed the problem and went to work to fix it. Not much help form the hundreds who read your post.

BTW.. My old rig does not have the pump rub pinhole yet so it's in the shop having the cure applied.

Dixon700 · January 30, 2018

If I would of got a manual for the transfer case it would of been a piece of cake. For a transfer case it was way more complex than the nv271d I rebuilt for my dodge. I'm a heavy truck mechanic so I have a good bit of mechanical know how. I just don't like blindly ripping into thing I don't know of. About 15k mi later my transfer case is still working great. This being an electronic shift with an electric axle disconnect just had me puzzled for a bit. Also should of payed better attention to how the snychronizer, blocker ring and mode fork was assembled. I should of took pictures by step for tear down.

Dixon700 · January 30, 2018

On 2/1/2016 at 10:43 AM, 00Silverado4x4 said:

Honestly for all the work that would need to be done, I'd pull the transfer case and get a new/rebuilt case. The pump rub issue is an internal problem. Until that pump retaining ring issue is fixed, no "repair" will work for very long. When I bought my truck, my case was in the same condition, pump rub, fluid burnt, chain was so stretched that it was actually hopping teeth when in 4x4. I didn't even try to have it fixed, just found a reserviced case to replace it.

I had right about $600-700 into the transfer case. You can't buy a junkyard one for that price otherwise a reman.

davester · January 30, 2018

I would take the encoder off the transfer case and see how well manually rotating the shaft worked (ie, that it rotates and shifts through all the gears, may take some wiggling of the front/rear driveshaft and you might need to get a rear wheel off the ground).

If it shifts fine, then you need to check:

-how the encode motor works (plug it in and see how it rotates)

-should be a sensor on the transfer case indicating what mode it's in. might want to test that it correctly works depending on what mode it is in (maybe test while doing your initial test of T.C. functionality?)

-test that the actuator in the front axle is engaging/disengaging (this only works if T.C. mode sensor is working properly)