Amp not powering up... What's going on?

I’ve tried 3 different amps and none of them are showing the power light. There’s 12v on the terminals until I turn the car on without starting the engine, then it drops to 1.5v on the terminals of the amp while the remote and negative are at 12v. Not sure what’s happening here… I even tried bridging the remote to 12v with the car off, but the power light still doesn’t turn on.

You’ve got 12V on the ground terminal? That’s not right. How are you grounding the amp?

Dakota said:
You’ve got 12V on the ground terminal? That’s not right. How are you grounding the amp?

Maybe I worded it wrong :joy: I meant measuring the voltages. The 12v is measured from the remote to negative. I’m grounding the car with the screw that holds the boot thingy in place.

@Juno
Can you take a picture of your amp’s ground for me?

Dakota said:
@Juno
Can you take a picture of your amp’s ground for me?

Here’s the pic: https://placehold.co/600x400.png

@Juno
What makes you think this is a good ground? Did you check the resistance with a multimeter?

I’ve seen bad grounds, and this one is definitely problematic.

Dakota said:
@Juno
What makes you think this is a good ground? Did you check the resistance with a multimeter?

I’ve seen bad grounds, and this one is definitely problematic.

I haven’t checked the resistance, but a lot of my friends have used this spot in their vehicles, and it worked for about a month until last week.

@Juno
Yeah, it worked until it didn’t. This sounds like a case of bad installation practices.

@Juno
When you throw your equipment in without securing it properly, or ground it to the smallest bit of metal in your car, don’t be surprised when things go wrong.

Fix your grounds or have a shop do it. Your install isn’t done right.

@Dakota
What kind of resistance should I be looking for when measuring from the cable to the negative on the battery?

@Dakota
I measured from the ground terminal to the negative on the battery, and got 0.5 ohms. I also lengthened the multimeter wire, which added 0.2 ohms resistance.

Juno said:
@Dakota
I measured from the ground terminal to the negative on the battery, and got 0.5 ohms. I also lengthened the multimeter wire, which added 0.2 ohms resistance.

The ideal ground has zero or near-zero resistance. Anything over 0.1 ohms is not acceptable.

This sounds like a grounding issue. I had the same thing happen. Sure enough, the bolt for my ground had come loose.

Everything showed 12V+ on all terminals, but when I tried to supply power, it dropped to 4V.

@Lin
It’s fixed! I replaced the ground terminal and sanded it down more. Also, it turned out the fuse was bad even though it wasn’t burnt through, so I replaced that too.