90 Chevy 1/2 Ton xfer case q

today was the first snowfall, and I discovered two things about my truck...

1) the tires suck. they looked in better shape before I owned it (father-in-law's old truck) and they'll need to go.

2) there's something "broken" in the 4wd system.

These are really embarrassing when you get stuck moving your truck so you can snowblow your driveway. (We got hammered with a foot of snow...)

Anyway, the problem is when I put it in 4hi or 4lo I discovered (minor) the linkage needs some (a lot of) grease (major) 4wd doesn't work. Well, it does, then it doesn't. The 4wd indicator light goes on and off and dim and bright, which I believe comes on when the front axle is engaged. After getting major stuck and letting the truck warm up I think the front axle finally engaged and I got out of the ditch.

I dug out the shop manual, and am a bit confused as to how the transfer case/front axle electrical works. I know 4wd works - I used it in 4low in my yard to move some engines a couple of weeks ago. (fluid levels are fine, the rear seal on the xfer case leaks but I just checked the levels on it and the diffs.)

According to the shop manual: There's the xfer case switch and a front axle switch, the solenoid/thermal activator in the front axle, and a clutch coil relay and a clutch coil. The description doesn't explain how all the parts work. I _think_ the xfer case is sending power to the front and the front hubs aren't locking, but not 100% sure. I'm going to go out tomorrow and see if the front driveshaft turns when I engage

4hi and the front tire isn't spinning on ice. (obviously a 2 person job... or I need to get all 4 tires in the air..)

I guess I'm wondering what the clutch coil relay and clutch coil do before I start replacing parts at random... (the truck is a stick shift if that makes any difference.) - do the front axle actuators "wear out" or stick as they get old? It was about -5C at the time and the truck had only gone about 50 feet before I got stuck...

I'm also thinking that the xfer case is a chain drive, so if it was busted it would be BUSTED and not work some of the time...

and upon further reading, it appears the clutch coil is only used for the "pushbutton 4wd" system, so my problem with the front axle light is probably the thermal actuator for the front axle? (it came on, then off, then on dimly, then off, then on and so on for a couple of minutes and finally came on solid...)

What do the experts think? :)

Ray

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