My first modification was to replace the two [joined] purple wires with a black (gnd). This is to provide the required gnd [switch return] for the relay (Relay nr. 5).
The original configured [2x purple wires] was looped from terminal 30 (12v live) back into terminal 86 (gnd), so these needed to be replaced with a gnd [return] for the horn to work. The [new] gnd feed was a direct spur from the gnd bus.
