99 1500 front differential roaring

:screwy: help! front diff. is roaring always when movine . doesn't matter if in 2 or 4 wheel . cane someone tell me in the input shaft between transfer case and diff. is supose to turn all the time. mine does and didn't know if this is right.
2 and 4 wheel works fine this in a push putton auto.shift
thanks in advance robbie

I believe it will turn all the time.

Have you checked the fluid level?

checked front greese and was black so something is not right
I check a 97 truck and the front input shaft only turn when in 4 wheel and is free when in 2 wheel.
This 99 truck has 2 wheel ,4 low and 4 high and auto 4 wheel push buttons maybe someone who has a 99 can check for me to see if theirs is free. I need to know if I have two problems. thanks again

I only know this from the blazer forums, but check your transfercase vacuum lines. Sometimes they like to pop off on the electric transfer cases. One reason im happy i've got the shifter.

pulled front ring and pinion and found pitted bearings and also found this post listed below when doing a search
thanks I found my answer

2000 silverado front driveshaft |
icerider []
AF Newbie
Joined: Aug 2004




08-23-2004, 01:13 PM 2000 silverado front driveshaft (Post #1)
My 2000 silverado z71 front drive shaft turns all the time even when it is not in 4wd. Is this normal? Does anyone have a solution?


simple_country_guy []
AF Regular



08-23-2004, 04:41 PM Normal (Post #2)
That is completely normal. You do not have lockouts on the front axle which means they stay connected at all times from wheel to differential to driveshaft. Your transfer case is where the driveshaft disconnects.

got to thinking about last post and thats not what mine does. My front drive shaft turns always with transfer case. I raised rear wheels and in 2wheel drive front shaft and ring and pinion spin with rear wheels ,only the axles are not locked in. anyone know anything else on this. It dosn't seem right to me.

The front driveshaft should not turn when in 2WD. I believe in your truck you will have 2 actuators. One on the transfer case and one on the front differential. It sounds as though the transfer actuator is froze. I have seen plenty of the fronts freeze up but not one in the transfer case. More than likely is possible.

Remove the actuator and have someone with the key on actuate between 2 HI and 4 HI. the actuator should move back and forth. Also, you might want to check for blown fuses as well as the relays.

If your 99 has the "Service 4WD" light, you might want to have it scanned.

Thank you. i'll post results later