Thank you for your response. Actually, none of those three scenarios apply in our case. My father died a few months ago and left my 91 year old mother with a great deal of things that need done and/or sold. In addition to numerous other things, my son and I are trying to help my mother fix and sell a couple cars my father owned. (My brother also passed away about eight months ago, and I am helping her with a lot of stuff concerning him as well. It is all so very overwhelming physically, mentally, and emotionally).

Now as for the Blazer problems. We did finally manage to get the radiator cap off. We will certainly try what you suggested. It is a great idea filling the radiator with just water until we find the leak. I also found a hand-held radiator pressure leak tester tool, so we can hopefully find out where the leak actually is. (My brother was a self-employed mechanic so he owned a lot of tools).

We also found a few BMII diagnostic scanners with my brothers stuff, but unfortunately none of them will turn on (even with fresh batteries). So I guess those will not be of help, with either the radiator leak issue, or the odometer issue.

But since the speedometer doesn't work and the odometer doesn't light up on the dash, I guess the odometer issue is most likely the speed sensor? Would this cause the odometer to not light up on the dash, even though everything else lights up?