Where to tap for signal to amp


I installed a amp/sub combo and have no pink wire(antenna lead) to splice for a signal to cut the amp on. I plugged into the battery port on the fuseblock and the unit worked. Just not sure where a safe place to get power from. My car originally had and still has a broken power antenna. The pink wire is not present going into the connector. Black,grey, and yellow are there. Any ideas??
Your radio should have a red wire on it,use that as a on an off.so if your radio is off your amp is off.

Sent from my SM-G930T using Tapatalk
Thanks blackazz! I'd like for be on only when the radio is on. I'll give it a try tomorrow and report back.
all gm radios have a P-ANT out , pin out for the radio is engraved into the case plate, you could have just added a pin at the empty spot on factory connector