I installed a nice double DIN Pioneer radio for a customer, but the AM reception was practically non-existent. Turns out the Gen2 Prius antennae needs power to pull in radio signals. It gets power from the radio. I solved it by hooking up the blue wire on the aftermarket harness adaptor to the red wire with a vampire T tap. Plenty of AM radio now...if that's what you're looking for.
How does this work with the OEM radio? I need some more detail as to the wiring. My guess the radio you installed didn't supply the power like the OEM radio does. Could it be that low AM is the result of low B+ voltage to the antenna AMP fom the OEM radio? I'll have to check that next time I pull the headliner down. It's too cold in Michigan now. I was going to beef up the grounding of the antenna by laying a wire under the 22 mm lug nut ( hammer the end flat to allow insertion) that mounts the antenna and run it over to the lip of the hatch back top and screw down the end to make a good positive connection. Thanks. Lee
