I removed a 40 amp buss fuse with a code of "CMH" becuase it had blown. The new one I put in blew also. The Toyota Tercel runs without it, but I would like to know what it is for. Everything seems to be working.

CMH stands for cold mixture heater. A relay comes from the fusible and goes to two items. A fuel heater and the cold mixture heater. Both of these are below the carb. in the intake manifold. I am trying to find out how to buy the cold mixture heater now. The car will run without it, but you may have trouble getting it to start when it gets cold..