Got a new car yesterday (1995 corolla) and today was attempting to install my head unit to replace the stock cassette deck in there. Done it a few times before on other cars, connected up all the wires no probs.
When I went to test it, it didn't turn on. Rechecked the connections, then tried using a wire directly from the battery to the power (not ignition) lead of the head unit, and it worked. Radio fuse was fine, but I changed it anyway, and I know it's all good there because the ciggie lighter works (same fuse for both lighter and radio).
So, does anyone know what the problem in the power wire (blue/yellow) could be? I don't really want to run a new wire from the battery (with a fuse in the middle).