Driving with diff lock and burning rubber smell

[Zsolt]

I was driving my '88 5ktq home yesterday in over -20C temperatures on
slippery, winter like roads. I had the diff lock on the first setting,
most of the way (about 150 km). (I like to drive like that when it's
slippery even on straight roads, it makes the car feel stable, if it
were on rails)

Just before I got home I started smelling a burning rubber smell inside
the car. It wasn't very strong and I thought it was another car I was
smelling, but when I got home and got out, I could smell it even more. I
turned the ignition off, and the smell disappeared with the exhaust in
the air. I looked under the hood, under the car, the tires, but I didn't
see anything out of the ordinary.

I restarted the car, but there was  no smell. What could've caused this?
Having the diff lock on? I also noticed a staticky clicking coming from
where the relays are over my left knee, and my green light on the diff
lock symbol as well as the yellow ABS OFF light in the dash would go on
and off intermittently the whole trip. (the lights have always done this)

Any ideas?

Thanks,
   Zsolt