LED Side Marker Circuit

I bought these side marker lights and was trying to figure out what the circuit is inside.

They say there are six LEDs which appear to be square white units like what you might see in lamps. I suppose color is determined by the lens.

I connected a variable power supply and plotted IV data for a few points. The ideal diode voltage varied between 6.7 and 8.8 volts across one sample of each color. The apparent series resistance is the same in each case, about 180 ohms. This makes me think the lamps are wired with two LEDs and a

540 ohm resistor all in series and the three strings in parallel with a single diode in series with the whole bunch to prevent damage if connected backwards.

Looking inside is not so easy as the lens has texture to spread the light. From the side I can see the diode and it looks like only two resistors. I don't see how three white LEDs could give an apparent diode drop of under 9 volts total.

Any ideas?

Actually my concerns are more about wiring these up so the connections are water tight and keeping water out of the lamps. They clearly have holes where the wires exit which I can easily seal. I can't tell if the lenses are well sealed which may be harder to fix. Maybe a job for methylene chloride and a capillary tube.

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Rick C 

Viewed the eclipse at Wintercrest Farms, 
on the centerline of totality since 1998