I don't know if there is a wiring diagram that is specific to the Euro GTS, but the wiring diagram that I looked at shows a red wire and a yellow wire at the speedometer. These are for the radiator fan indicator light. Only one gets connected to the indicator light. The red wire comes from the low temp fan relay and the yellow wire (you guessed it) comes from the high temp fan relay.
Actually, the wiring diagram has an error. It shows two yellow wires at the speedometer, but one of them is marked red at the low temp fan relay. The wiring diagram shows it as a continuous wire with no splices or taps.
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