I'm not sure why the indicators (the turn signal indicators or the warning lights?) would dim when turning the headlight switch. I'll defer to Salmon's experience on this one.
Per Salmon's advice, there are 2 flashers - one is plugged in to the fuse block and the other is clipped to the backside of the dash just to the right of the steering column. The electrical diagram shows that the fuse block flasher is the emergency flasher.
Yes, the 4A inst fuse is powered by a green wire coming from the headlight switch. It is not powered until the switch is pulled out, and the circuit is powered through a rheostat in the switch. Turn the knob counter-clockwise for full voltage. As you turn the knob clockwise, the voltage will decrease. Fully clockwise will turn the lamps off.
Does your instrument cluster have gauges or warning lights? Is it possible that someone re-wired or miswired the connector in the past? The connector pinout is different between the 2 types of clusters. Go to the FGF - FAQs - Dash and Instruments page and scroll about 1/4 of the way down to an entry titled "Q: Stock Cluster to a Rally Gauge Cluster". In the answer there is a good description of the connector pinout and wire colors for each type of cluster.
