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Discussion Starter #1
So I got a new alternator put in to the commander last week and since then my kenwood flip out radio doesn't come on or turn off when the car is turned on or off, I have to manually turn it on or off. Also my subwoofer amp is not working after the new alternator, the three power lights are just blinking. Not sure what is going on or if anyone on here would know
 

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Have you put a multi-meter on the electric system and check the actual voltages being made by the alternator?

Do you know the amp rating of the new alternator? Or the old alternator?

Do you have a PAC CAN interface wired to your radio?

Look up the literature for your amp and find out what the blinking power lights mean. Have you tried to jumper the turn on power lead to the AMP and see if it turns the amp on?
 

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Discussion Starter #3
took it by the radio shop to see if they knew anything and he noticed that my rpms kept dropping and it was idling hard which has been going on since the alternator replacement. The guy said it could be the belt not being in sync and it not getting enough voltage to the radio and amp. So I'm going to carry back by the mechanic and have him check and then I'll do the stuff you recommended. Its just crazy that it was working perfectly fine before.
 

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...The guy said it could be the belt not being in sync and it not getting enough voltage to the radio and amp....
Ummmm, accessory drive belts do NOT sync, that makes no sense. Perhaps miscommunication, but it doesn't sound like he knows what he is talking about. A quick inspection of the belt should tell if its the belt or NOT, as well, you'd have lots of belt squeel if it was slipping. Its always possible the pulley's aren't lined up correctly (something would have to be wrong with the alternator out of the box for that to happen), but again, you can tell that by just looking at it at the right angle.
Its just crazy that it was working perfectly fine before.
Did you replace the alternator because it was failing/failed with a new/rebuilt direct replacement?

-OR-

Did you replace the alternator with an aftermarket alternator that has a much higher current output to power your amp and stereo?

It makes a world of difference? An aftermarket hi-output alternator may have had special instructions for the install and your mechanic may have just swapped it like a direct replacement for OEM.

When you visit the mechanic, have him measure the voltage of the system, it is very possible there is something wrong with the new alternator and it is producing the wrong voltage and your electronics are NOT working correctly because of the incorrect voltage.

The fact the motor is idling poorly also makes me suspect a bad alternator out of the box, its possible low voltage or irregular power supply is making the engine management electronics go nuts, or its even possible the alternator has a bad bearing out of the box and the alternator is failing and startign to seize right away, the resistance from the alternator is dragging down the engine idle.

Take the belt off and spin the alternator by hand, it should spin smooth and freely, if its rough or has resistance, the alternator is bad.
 

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Discussion Starter #5
Thanks for all your help, and yea I kind of thought the guy at the radio shop didn't really know what he was talking about, but maybe he did just didn't communicate it clearly. The alternator was replaced because the old one was about to go bad. As far as I know its just the same one as the stock, not a hi-output or anything like that. That might be good for my setup? Anyway, its in the shop now, I should know something later today and I'll let you know what they say.
 
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