Topshelf

For some reason my aftermarket stereo will NOT power up or down the antenna. I don't understand it. I metered 12v going to the lead with the original radio. And there is 12v coming off the lead of the new one. WTF? If I play with the wire I can hear 2 things. The sub kicking in and out and a clicking noise. This makes sense since the wiring diagram show that lead as the Amp Power and Antenna Lead. It sounds like there is a relay or something back at the antenna that is making the clicking noise. But if 12v is getting to it with both stereo's, why does only the old one work???

Any suggestions?