Car Stereos: amp wiring, hyundai santa fe, digital multimeter

Question
hi, i wired an amp for the first time last night and it works sweet when the key is in acc postion, i put my remote on a toggle, ran a wire from the battery, grounded to a bolt right near the amp.
when i start the car (04 hyundai santa fe) the amp turns off and will not turn on. no fuses blown. can you help? appreciate it much.

Answer
Hi Adam,

That's an unusual problem, but I can think of a few possible causes.  To figure it out, you'll need a digital multimeter so you can test the voltage at the amplifier's power terminals.

To test the voltage, set the multimeter for DC Volts, 20v range (if it's not an auto-ranging meter).  Place the black probe on the amplifier's ground terminal, and use the red probe to test the voltage on the power terminal and remote terminal.

If the voltage on both terminals tests between approximately 11 volts and 15 volts, and the amplifier isn't turning on, then there must be a defect in the amplifier.

Here are the other possibilities:

You may find a low voltage on the power terminal, and normal voltage on the remote terminal.  In this case, it probably means that there's a poor connection at the battery or at the fuse holder, and it's being aggravated by the vibration of the engine.  

You may find a low voltage on the remote terminal, and normal voltage on the power terminal.  In this case, it could mean that your remote wire is connected to the wrong voltage source.  For example, there are some illumination wires that will show voltage with the lights off, and no voltage with the lights on.  If your remote wire is connected to this type of power source, and the vehicle is equipped with automatic lights, then that could cause the remote wire to lose voltage when you start the engine.  The fix would be to switch the remote wire to a different power source.

You might see low voltage on both terminals when the engine is running.  In this case, I'd try a different ground point for the amplifier.

Finally, there's a slim possibility that you'll see a voltage higher than 15 volts on the power terminal when the engine is running.  This would indicate that there's a problem with your vehicle's voltage regulator or alternator, resulting in too high a voltage set point.  Many amplifiers will shut down if the supply voltage is too high.  If you see a voltage level above 15 volts with the engine running, you should have your vehicle's charging system checked as soon as possible.

Hope this helps!

Brian