4x4 Not Engaging

[Zeppelin264]

Ok well i have a 2001 Sierra Z-71 4x4 and the 4wd dosent work anymore, it worked 3 weeks ago and inbetween that time and now all i did was replace the front outer axle seals and now it dosent seem to be getting power to the front from the transfer case.

 

Its odd because when you engage the 4x4 from the push button, i can hear all the actuators working like they should but when u give it power no front tire spin. Also when i was checking fluid levels i noticed that the T-case has a "red" fluid like ATF and I think it needs to be the "blue" autotrac 2 stuff, maybe the clutch packs in the t-case burned up?

 

Also i noticed when u put the T-case in Neutral, and u put it into gear there is a really bad sound coming from the T-Case almost like a slaping piston or broken Rod in a motor. What could that be?

 

lastly is there any way to run a check on the actautors? Im a tech as well but not for GM's, lol just lil honda's and toyota's, so this is all new to me. Any advice would really help

 

 

-Rich

[Ranger]

If you're talking about the transfer case coming out of neutral into 2hi and making the noise, my truck does the same thing.

 

It's possible that your front actuator isn't working. It's pretty simple to change, simply unscrews from the front diff and is attached to a harness with a breakaway connector. I think the part usually costs about 80 bucks, it did for my buddy's 91 K2500 Sierra.

[Zeppelin264]

Yea i already tried that and it apears to be working like it should, i think the problem lies within the "Encoder motor" of the transfer case, but i have no clue what that is.

[TBLAZER]

Yea i already tried that and it apears to be working like it should, i think the problem lies within the "Encoder motor" of the transfer case, but i have no clue what that is.

The encoder motor is the one attach to the transfere case and if it has a problem the "service 4wheel drive" message will appear on the cluster,The 4 wheel drive control module is under the dash and it controls the encoder motor and the front axle actuator it also stores trouble codes when any.

When shifting from 4WD low or out of nultral the transfere case will almost always clunck or make some kind of load noise,this is normal,the original autotrak fluid was red/pink in color the new and inproved autotrak fluid is blue and it looks like it's time to change the t-case fluid with the new stuff,2 quarts will due it.

Fist you need to check and see if you have power and ground going to the axle actuator with the ignition "ON" and the 4WD engage.

Front actuator 4 way connector pins are;

A-BLK/WHT-Axle Switch Signal

B-LT BLU-Axle Actuator - Control

C-BRN- Ignition 3 Voltage(12Volts)--------------(if no voltage check the ignition 3 fuse)

E- BLK-Ground

you can also add external power and ground to the actuator to test it.

[Zeppelin264]

Hi,

 

Thanks for the informative response. I pulled the actuator out of the front diff and when engaged it moves like it should, so i know there is power to the actuator. My problem is that when u engage 4wd hi or low everything works like it should(lights all work, T-case moves, actuator moves). I removed the front drive shaft and the T-case is not turning the front driveshaft, therefor no power to the front diff and no 4x4.

 

Thats why i think its the t-case encoder motor, becasue it sounds like its working but there is no power to the front axle. Ive heard of one other person that had this problem and he replaced the encoder motor and it fixed it all. I just dont want to spend the 300.00 bucks or whatever for a part if its not bad.

 

Also is my T-case the 2 speed selectable or the 1 speed auto. I think its the 2 speed selectable, but i want to be sure beacasue there are two choices for encoder motor's. Its the Z71 1500 T-case with autotrac.

 

Thanks,

 

 

-Rich