Most current car head units requires two (2) kinds of B + supply; the yellow should be connected to an always on/constant B+12 such as the positive terminal of the battery. This is responsible for the memory and setting/configurations not to be erased when powered off. The red wire is connected to a switchable B+12 such as the ACC terminal of the IGN switch making the radio work only when the key is turned to ACC. Of course,the black is connected to the chassis/ground.
Hope this be of initial help/idea. Pls post back how things turned up or should you need additional information.
Answers & Comments
Hi,
Most current car head units requires two (2) kinds of B + supply; the yellow should be connected to an always on/constant B+12 such as the positive terminal of the battery. This is responsible for the memory and setting/configurations not to be erased when powered off. The red wire is connected to a switchable B+12 such as the ACC terminal of the IGN switch making the radio work only when the key is turned to ACC. Of course,the black is connected to the chassis/ground.
Hope this be of initial help/idea. Pls post back how things turned up or should you need additional information.
Good luck and kind regards.
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