The orange wire is the remote on for the amp and power antenna. The MK1 doesn't have a headlight sense (dimmer) input

(list 6284, Mk1 S/N 00299 4GB blue [for sale]. Mk2 S/N 080000094 6GB blue)
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(list 6284, Mk1 S/N 00299 4GB blue [sold]. Mk2 S/N 080000094 20GB blue)