Radio and water don't mix

[murfethesurf]

I have stock radio in 92 XLT. When I start the engine, radio comes on ok. If I pull headlight switch radio will quit and come back on. But when the car gets wet from rain radio will not come until something somewhere drys out. Because the radio is wired into the lighting/turnsignal circuit and I have the tow package I am suspect of the switching circuit in the rear compartment. Anyone experienced this. The radio works fine, but there is a gremlin the circuit.