Left rear blinker inner bulb malfunction after replacing factory Shaker 500 radio

05MustangMark

Left rear blinker inner bulb (right bulb of the three in the set) malfunction after replacing factory Shaker 500 radio. I examined the bulb and it looked fine. I switched it with the center bulb of the three bulb set. The bulb works in the center position and now the former center bulb does not work in the right position. Then I returned the bulbs to the original positions and the original problem returns.

In each case, what ever bulb I placed in the right position did not work there but worked in the center position.

This occurred after I replaced the factory radio with a Kenwood radio.

Any ideas?

Thanks

thecardoc3

Did you test for power and ground to the socket?