Voltage Issue - Chevy Colorado & GMC Canyon
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post #1 of 3 (permalink) Old 07-05-2016, 02:06 PM Thread Starter
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Join Date: Nov 2014
Posts: 3
Question Voltage Issue

I recently installed some subs and an amplifier in my 2007 Canyon with the 3.7L. In order to fix the dimming, I installed a small XS battery under the seat. I also installed a digital volt meter on the amp itself. I bought a brand new main battery and new terminals. When I first started the truck, the meter would go up to 15.3 and stay there for 30 seconds. Then the voltage slowly drops and stays at 14.7 for a minute and then it slowly drops down to 12.8 and stays there. Now when the bass hits, my voltage drops down to 11.6.

I figured the voltage regulator was shot, so I went out and bought a new alternator. I installed it today. It does the same exact thing as the old one. It doesn't go up to 15.3 anymore but it still sinks down to 12.8(battery voltage) and stays there. Why isnt the alternator kicking? Every once in awhile, I will see it go up to 13.7 and then sink back down to 12.8. Even with the truck running, AC on, radio playing, it will stay at 12.8. It goes down when the bass hits but then back up to 12.8. When its on 12.8 volts, it will drop down to 11.5 volts. When I play the music right after I start the truck up and have 14.5 volts, the voltage will only drop down to 13.2 or so. How can I get it to stay like that?
FLPatsFan12 is offline  
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post #2 of 3 (permalink) Old 07-06-2016, 09:20 PM
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Join Date: Jan 2006
Location: Nutley, NJ
Posts: 1,660
If you take the amp out of the system (disconnect it at the battery) does it still have the same problem?
I ran my 2005 with a stock alternator and 2 amps and a 10" sub for 10 years and never had any charging issues. You have changed the alternator and still having a problem which hints to me that maybe the problem was there before you installed the amp and are just now noticing it as it is getting a bit worse?

Also, are you using the proper gauge wire to feed the amp?

2005 5 cyl, Black on Black, 4 door
2016 Z71, Black, Long Box, 4 door
Toughsox is offline  
post #3 of 3 (permalink) Old 07-07-2016, 01:12 AM
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Join Date: Apr 2009
Location: Hebron, Indiana
Posts: 2,566
You need to look at the voltage at it's source. If it is not low, then your problem is with the cabling or the ground return. Read the +12 voltage as close to the alternator as practical and use engine for your ground reference. The frame is NOT part of the ground system.

So what is the maximum current draw of this device?
What gauge cable did you use for both the +12 volts and the ground?
What is the length of these cables?

The power source for all things 12 VDC is the alternator, NOT the battery and the master ground is the engine, NOT the battery or the frame.

One other thing is the alternator is controlled by the computer and is slow to respond to voltage / load changes. If you want to see this in action read the voltage as you are starting the engine and watch for the alternator to turn on. It is delayed for a few seconds after starting the truck. I forget at the moment where the voltage is sensed by the computer to change the alternator output. If you really what to know, I'll dig it out of the wiring diagrams for you.

Good Luck

2005 White 2wd Z71 WT
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