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Discussion Starter #1
Hello. New guy (but 62 yrs old...) trying to keep my son's truck running until he graduates college. (about 1 more year!).
Recently the 4WD indicator/switch has taken on a life of it's own. (Sometimes being in 4WL when started, no lights showing on the switch at times, not being able to change from 2WH to 4WH, etc) He lived with this condition for a couple weeks but this week it has gotten worse. It was stuck in 4WL and seemed like it was not going to change. It is showing a "Service 4WD" message. I've also noticed a slight "growling" noise coming from the transfer case when moving in 1st gear. Noise disappears after it shifts to 2nd. This noise happens in all transfer case ranges.

What I've done so far:
-Confirmed the front diff actuator is working.
-Found ohm specs on line for the dash switch and all buttons are spot on.
-Checked transfer case fluid level. It was low. (It only had about a cup! But no metal bits. I could not find any pin holes in the case from pump movement. There was 2-3 bits of clutch material (I think)...about 1/6" in size in the drained fluid.) I refilled with 2 qrts of Valvoline fluid. After fluid change the growling was still there but maybe not quite as loud.

While doing the above work the 4WD began working again (I was able to shift into all ranges). Later in the day the switch was showing it was in the "Auto 4WD" range but I was able to switch it to 2WH.

Some additional info:
-Since we've owned this truck, when using 4WL, the transfer case makes a pretty loud "clunk" when engaging or disengaging.
-We've had the transmission rebuilt about a year ago with HD shell and clutches.

I'm thinking the transfer case needs a rebuild (from running almost dry?....) and the encoder in the TC shift motor needs replacement. Any help or advice would be appreciated.

thanks
 

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Discussion Starter #2
So I pulled the transfer case and disassembled. I was surprised to find it in very nice shape except for the large amount of black silicone someone used to seal the case halves. (This despite having low oil level.) I reassembled the TC and replaced the encoder in the shift motor. (That cured the "Service 4WD" message. Noise is from the transmission planetary gear set. Fortunately I still had two days before the 12 month warranty was up on trans rebuild.
 
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