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Old 04-16-2017, 03:22 PM   #1
raymondbray

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Amp powering on without Remote wire plugged in

2015 Chevy Cruise, P-AAGM44-PLAB PAC - Wiring harness and output converter, MRX-M55 Alpine amp, Alpine control knob.

Basically, I have the PAC plugged into the factory Head Unit, RCA's running back to the alpine amp with a 12" JL Audio sub, 4 gauge power wire run to battery, 4 gauge ground wire bolted where seats bolt to frame and also had a separate REM wire fuse tapped into the fuse box with accessory fuse to control amp.

When everything is plugged in the sub works great, no weird sounds or anything. But unplugging the REM wire doesn't turn the amp off, the amp turns on and off when the white (Left) RCA cable has power going through it. So, there's no REM wire hooked up, but the amp still gets powered on when i turn the key, and then shuts off about 10 seconds after turning car off, so the system seems to work fine.

Worth noting that once the ignition has been turned off, every few times, in the 10 seconds the amp stays on, the sub will start to rumble very loudly for the last 3-5 seconds, until the amp turns off.

This is why i started testing the REM wire in the first place. If it was working properly, the amp power should be cut before this sound is made. Have tried completely different RCA cables and both do the exact same thing. Have also been using a multimeter to test the voltages running through the RCA cables, and tested the REM to ensure the power is on with ignition, and off when car shut off.
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Old 04-16-2017, 09:41 PM   #2
KaeZoo

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So when you unplug the left channel RCA cable, the amp shuts off? Does it work the same way with the remote wire connected and powered, vs. without the remote wire connected?

Do you have the amplifier's high-level input plug connected?

What voltage are you seeing on the RCA cables when you use your multimeter? Specifically, if you set the meter for DC volts, with the black probe on the amp's ground terminal and the red probe touching the center pin on the left channel RCA cable (unplugged from the amp) what's the reading?
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Old 04-17-2017, 01:23 AM   #3
raymondbray

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Quote:
Originally Posted by KaeZoo View Post
So when you unplug the left channel RCA cable, the amp shuts off? Does it work the same way with the remote wire connected and powered, vs. without the remote wire connected?

Do you have the amplifier's high-level input plug connected?

What voltage are you seeing on the RCA cables when you use your multimeter? Specifically, if you set the meter for DC volts, with the black probe on the amp's ground terminal and the red probe touching the center pin on the left channel RCA cable (unplugged from the amp) what's the reading?
No RCA, Yes Rem - Instant on with key on, instant off with key off
Yes RCA, Yes Rem - Instant on with key on, delayed off with key off (turns off when factory head unit loses power)
Yes RCA, No Rem - Instant on with key on, delayed off with key off, same as with rem plugged in

Voltages with neither plugged into amp: 5.25 on red inside, and red shield, 5.24 on white inside and white shield.

When one is plugged in:
(red in) white voltage: 4.0
(white in) red voltage: 3.7

Also, when no REM wire, and one (either) RCA cable plugged in, it turns on, and when unplugged the power light turns off for 2 seconds, back on for 1 second and then off again.

Also nothing plugged into Speaker Input - so the Auto on should not be activated, correct?
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Old 04-17-2017, 08:46 AM   #4
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You might try placing a ground loop isolator between the PAC module and the amplifier.

I haven't run into this problem before, so I'm speculating. But my guess is that the DC voltage you're seeing on the RCA cables is what's keeping the amplifier on. Some amplifiers are designed to work this way, especially models that can accept high-level inputs through the RCA plugs instead of using a separate speaker-level input. Because your amplifier does have a separate high-level input plug, I wouldn't have thought the Alpine amp would switch on with DC on the RCA inputs, but it does have an auto-on function that's used with the speaker-level inputs.

The factory speaker outputs normally have a DC offset that can be measured whenever the head unit is switched on. Many line output converters use transformers which would remove the DC voltage, but some just use resistors, and I suspect that's the case with your PAC module. A ground loop isolator uses transformers to break the direct connection between the head unit and amplifier, so installing one in your system should remove the DC on the RCA outputs, which may solve your problem.
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Old 04-18-2017, 10:58 PM   #5
SPL_Krayzie112

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Can you shuffle the connections around? (e.g. red rca goes to white, white rca goes to red) and see if it still does the same thing?
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Old 04-19-2017, 12:41 PM   #6
jepalan

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This sounds like a grounding issue. Seat bolt is not always a good ground point. Did you grind off paint from chassis where amp is grounded? Try a different ground for the amp.
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