Stock HU with two antenna plug?

[TRD04RUNNER]

I notice when I remove my stock HU (regular single dish non JBL)their was 2 antenna looking thing plug into the back of the stock HU. their was a normal size plug and a smaller plug. I only use the normal size antenna when I install my alpine but what is the smaller antenna looking plug for?? should I use that one too? where can I get a y adapter for a small and normal size antenna male plug to hook both of them up so I can bet better reception?

 

[sharp4runr]

They 4Runners have a Diversity antenna. If you look at the side windows in the cargo area, you'll see filament running through them almost similar to the defroster wire in the rear. These are actually the antennas. The radio will switch between the two depending on which has better reception.

Sorry can't answer your other question about the y-adapter.

 

[greasefingers]

Correct me if I am wrong, but you cannot use a Y-adaptor. The stock HU circuitry measures the two antenna signal inputs and chooses the strongest one. It may even alternate between the two antenna