Amp has power but won’t turn on… Any ideas?

Been trying to get my car audio system running, but I’m stuck with a problem. My XD400/4v2 amp isn’t responding at all when I turn on the car. I’ve checked with a multimeter and am seeing around 12V at rest and 14.29V when the car’s on, so it’s getting power.

I’ve also got a subwoofer amp hooked up, and it works just fine. I even tried swapping the remote wires between the amps – the sub amp still worked, but the XD400 wouldn’t power on. Has anyone run into this issue before or know what could be causing it?

Have you looked into the remote wire and the power supply? Maybe try disconnecting the speakers to see if they’re the issue, or it could just be a bad amp.

Ezri said:
Have you looked into the remote wire and the power supply? Maybe try disconnecting the speakers to see if they’re the issue, or it could just be a bad amp.

I tested both remote wires on the sub amp, and they’re working fine there, so I don’t think it’s the remote wire. Any tips on how I should go about checking the power supply?

Ezri said:
Have you looked into the remote wire and the power supply? Maybe try disconnecting the speakers to see if they’re the issue, or it could just be a bad amp.

Tried running the XD400 without any speakers connected, but still no luck. It’s just not powering up at all.

If you’re seeing 12V between the amp’s power and ground terminals, and also 12V between the remote and ground, it could be an issue with the amp itself. The only thing to watch for is that sometimes, even if it shows 12V at the terminals, when you try to power it on, the voltage might drop, which could mean a bad connection somewhere.