4 Wheel Drive/SUVs: 1998 Bravada Service All wheel drive lite

Question
Bravada has 163000 on it.All wheel drive not working but no light on dash,til we replaced the atc (active trnsfer case) fuse.Reset with computer after taking out box on passenger side kick plate.Got another box from junk yard,put it in and service all wheel drive light came back on,and still of course just rear wheels spin,no all wheel drive.Was told possibly a corroded wire or switch.All wheel drive went in and out last winter occasionally.I understand you are not an expert,just looking for another opinion.Thank you kindly in advance!!

Answer
Ken,

I would get a repair manual, and a multimeter, for the Bravada, and check out the wiring diagrams.  With these two items, you will be able to trace out the wiring, and test for faulty grounds.  Bad grounds to the transfer case, and corroded or broken wires, not uncommon problems.  Many of the 4x4s in this year range, use a disconnect on the front differential, which may be electric, or vacuum.  If it has this, and it is faulty, you will not be able to engage the front end.  You can find this out in the manual also.

Carl