Radio wiring
It is IMPORTANT to understand how the instrument lamps work, and as a matter of fact, important to understand how other wiring works
1...The red at the radio connector comes FROM the key "ACC" contact and the fuse panel. It provides 12V for the radio, and is branched off at various points for a couple other loads. IF THE wiring has been hacked up, either/ both the red or the orange circuits may be compromised
2...The instrument lights are a TRICK. The headlight switch has TWO power sources. ONLY the headlights are fed to the HL switch B1 from the ammeter wire welded splice and ARE NOT FUSED. The headlights circuit has a breaker in/ on the HL switch
The second power sourced comes from a fuse, always hot, in the panel, which feeds tail/ park and instrument lamps. For the inst lamps to operate, the tail/ park lights must be operational FIRST. So with the HL switch in either park or full out, that action powers the instrument lamp dimmer control (twist the knob.) So the knob MUST be twisted somewhat to the left, and the control can get dirty, so twist/ wiggle the knob several times. THAT POWER, the output from the dash dimmer control, then leaves the HL switch on TAN, goes TO the fuse panel INST fuse which is the small fuse at one END of the panel. That power then goes from that fuse on orange wiring to all dimmer controlled dash lighting.