OVP relay perhaps? I think they can cause weird problems like this. I think what dirtyharry meant was are the lights warning lights in the instrument cluster or other lights in the dashboard.

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Streetside: 1987 Mercedes 300E Petrol Blue/Green
2014 Ford Mustang Grabber Blue
1999 Ford Ranger Green

Dockside: 1968 Eltro 17
1985 Silverton 34C