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Discussion Starter · #1 ·
So I'm getting this apparently somewhat common issue in the Gen1 Cruze, that the headlights are giving some kind of interference to the audio system of my car. A constant level buzz, mainly audible through the tweeters.
I think the issue is my LOC, since the buzz is not affected at all by the (stock)headunit volume, but my LOC has an output level control, and turning the level higher, the buzz similarly gets louder.

I tried wrapping the whole LOC in aluminum foil, along with most of it wiring, with no effect on the buzz at all. Also tried wrapping the drivers' side crossover in foil at the same time, no effect at all.
Then I tried changing the grounding point of the LOC from the existing ground point near the drivers' seat directly to the battery negative: no effect whatsoever.

Some people apparently have "fixed" this by moving their crossovers away from the front of the car, but I'm kind of sceptical about this, since the aluminum foil had no effect on the buzz in any way.

This is the full audio setup currently:
  • Stock headunit
  • LOC wired to the front speaker wires coming from the HU near the drivers door. LOC is grounded at the existing grounding point next to the drivers seat/foot space. LOC gets its 12V power from the fuse box under/next to the steering wheel.
  • RCA cable going from LOC to an amplifier in the trunk, also remote wire LOC -> amp
  • Crunch amplifier installed in the trunk, grounded on the existing ground spot at the back of the rear wheel well on the drivers side.
  • Amp powerline coming in from the battery behind the pedals, routed to trunk in the passengers side.
  • DD-audio passive crossovers under/inside the dash on both passenger and drivers side.
  • Speaker cables routed in the same place as the amp power and going to crossovers, and then continuing to the tweeters in the A-pillars, and to the woofers in the doors.
  • DD audio Redline 6.5" woofers and tweeters from the same set.

Other things I've tried:
Removed the screws that hold the amp in the back of the backseats, so as to remove any connection between car chassis and amp chassis: no effect.
Removing RCA cables from either end, LOC or amp, gets rid of the noise -> noise comes from either HU, or LOC. HU seems an unlikely source, as the stock speakers did not buzz this way.
Turning the headlights off gets rid of the noise. Unfortunately that is not a good solution :D

I've seen other threads about this, and I've spent a ton of time reading through them but seems no one has found a clear solution to this.

Any ideas?
 

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So I'm getting this apparently somewhat common issue in the Gen1 Cruze, that the headlights are giving some kind of interference to the audio system of my car. A constant level buzz, mainly audible through the tweeters.
I think the issue is my LOC, since the buzz is not affected at all by the (stock)headunit volume, but my LOC has an output level control, and turning the level higher, the buzz similarly gets louder.

I tried wrapping the whole LOC in aluminum foil, along with most of it wiring, with no effect on the buzz at all. Also tried wrapping the drivers' side crossover in foil at the same time, no effect at all.
Then I tried changing the grounding point of the LOC from the existing ground point near the drivers' seat directly to the battery negative: no effect whatsoever.

Some people apparently have "fixed" this by moving their crossovers away from the front of the car, but I'm kind of sceptical about this, since the aluminum foil had no effect on the buzz in any way.

This is the full audio setup currently:
  • Stock headunit
  • LOC wired to the front speaker wires coming from the HU near the drivers door. LOC is grounded at the existing grounding point next to the drivers seat/foot space. LOC gets its 12V power from the fuse box under/next to the steering wheel.
  • RCA cable going from LOC to an amplifier in the trunk, also remote wire LOC -> amp
  • Crunch amplifier installed in the trunk, grounded on the existing ground spot at the back of the rear wheel well on the drivers side.
  • Amp powerline coming in from the battery behind the pedals, routed to trunk in the passengers side.
  • DD-audio passive crossovers under/inside the dash on both passenger and drivers side.
  • Speaker cables routed in the same place as the amp power and going to crossovers, and then continuing to the tweeters in the A-pillars, and to the woofers in the doors.
  • DD audio Redline 6.5" woofers and tweeters from the same set.

Other things I've tried:
Removed the screws that hold the amp in the back of the backseats, so as to remove any connection between car chassis and amp chassis: no effect.
Removing RCA cables from either end, LOC or amp, gets rid of the noise -> noise comes from either HU, or LOC. HU seems an unlikely source, as the stock speakers did not buzz this way.
Turning the headlights off gets rid of the noise. Unfortunately that is not a good solution :D

I've seen other threads about this, and I've spent a ton of time reading through them but seems no one has found a clear solution to this.

Any ideas?
Welcome Aboard!(y)

These are just swags:

You could have a ground loop
You could have a set of speaker wires reversed
The LOC could be faulty

Don't forget to introduce yourself and you Cruze here.
 

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Discussion Starter · #3 ·
Thanks for the welcome!
Do you happen to know where the stock head unit is grounded to? I'm guessing if I have ground loop issue here, it would probably be between the LOC and the HU. I could try grounding them to the same place, but I'm a bit sceptical about this as well, since I already tried to ground the LOC straight to the battery negative, with no luck.

One thing could be the amp ground, but it seems weird (although I'm not an electrician) that it could be the issue, since it seems the source of the buzz is either the LOC or the HU.
 

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You may want to try moving the amp ground its own spot, not sharing ground with anything else. I have my amp grounded to the lower latch restraint in the back seat. Also try moving the RCA away from any power wire, amp or remote wire. Usually I run the power and remote wire along one side of the car and the RCA on the other side or through the middle of the car.

Usually the stock head unit is grounded directly behind it to the dash but it could have a couple grounds too.
 

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Discussion Starter · #5 ·
You may want to try moving the amp ground its own spot, not sharing ground with anything else. I have my amp grounded to the lower latch restraint in the back seat. Also try moving the RCA away from any power wire, amp or remote wire. Usually I run the power and remote wire along one side of the car and the RCA on the other side or through the middle of the car.

Usually the stock head unit is grounded directly behind it to the dash but it could have a couple grounds too.
I'll have to try that grounding point for the amp you mentioned, at least it should be pretty quick to test.
All other power wiring is on the other side of the car from the RCA except the remote wire, since I forgot about it when I was finishing the installation and then just put it on the same side as the RCA. I thought that it is so low current that it shouldn't mess with the RCA, but who knows. If the amp ground change won't help, I guess I'll try removing the remote and giving a manual wake up for the amp and see if anything is different.
 

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Discussion Starter · #8 ·
So just now I tried digging the RCA cable out from under the panels on the drivers side: not even the slightest effect on the buzz no matter where I have it. Then I tried moving the amp ground to one of the bolts holding the rear seats in place after sanding out the paint around it: zero effect on the buzz.

Also noted that sometimes, for no apparent reason, the buzz quiets down to a much more manageable background noise, but will after some time come back to the way it was. This is when the engine is running (obviously, since the headlight buzz doesn't happen when the engine is off)
 

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So just now I tried digging the RCA cable out from under the panels on the drivers side: not even the slightest effect on the buzz no matter where I have it. Then I tried moving the amp ground to one of the bolts holding the rear seats in place after sanding out the paint around it: zero effect on the buzz.

Also noted that sometimes, for no apparent reason, the buzz quiets down to a much more manageable background noise, but will after some time come back to the way it was. This is when the engine is running (obviously, since the headlight buzz doesn't happen when the engine is off)
I mean are they LED or something?
 

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Discussion Starter · #12 ·
There are yellow leds.
I know, but they are very rarely if ever installed as stock lights in cars. All LED headlights I've seen have been blue/white. I think halogen bulbs are the stock lights on this model, and this headlight buzz has been an issue for so many users that I doubt every one of them has changed their lights to LEDs.
 

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I know, but they are very rarely if ever installed as stock lights in cars. All LED headlights I've seen have been blue/white. I think halogen bulbs are the stock lights on this model, and this headlight buzz has been an issue for so many users that I doubt every one of them has changed their lights to LEDs.
Previous owner could of added them.

The LEDs don’t cause problems but the power supply does. Iirc a power supply to do this is gonna be like $300. Sooooooo tell me how you fit that in a $50 bulb.
 

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Discussion Starter · #14 ·
Previous owner could of added them.

The LEDs don’t cause problems but the power supply does. Iirc a power supply to do this is gonna be like $300. Sooooooo tell me how you fit that in a $50 bulb.
At this point I have no idea what you're going on about.

Anyway, now it seems that after driving just a short time, the buzz gets significantly quieter. This didn't happen before moving the RCA cable and amp ground, but I only did one or two test drives back then. Guess I'll just have to do all my driving with this car for a while and see if this happens consistently. The quiet buzz is easily drowned out by the music and car noises.
Still curious what could cause this change in the noise though..
 

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At this point I have no idea what you're going on about.

Anyway, now it seems that after driving just a short time, the buzz gets significantly quieter. This didn't happen before moving the RCA cable and amp ground, but I only did one or two test drives back then. Guess I'll just have to do all my driving with this car for a while and see if this happens consistently. The quiet buzz is easily drowned out by the music and car noises.
Still curious what could cause this change in the noise though..
Did you buy it used or not?
 

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Discussion Starter · #17 ·
Has anyone experienced this headlight buzz with an aftermarket head unit / radio? If not, I'm starting to think it makes no sense going through this much trouble with the stock HU if simply replacing it gets rid of this issue.
 

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Discussion Starter · #18 ·
I think someone else also had this louder buzz seemingly randomly quieting down at times. I wonder if this could have something to do with the automatic light system? My car does not switch the headlights off even when it's bright, but it seems that this "random" change in the buzz volume could have something to do with the automatic lights, since earlier today I was driving around when it was cloudy and the buzz never went quieter, but later on when the weather changed to sunny, the buzz again quieted down after driving just a couple hundred meters after starting the car. Not sure what even happens when the system detects that it is bright/dark outside, but there has to be some electrical device that changes it's state (either something related to this light system, or maybe something else entirely), otherwise the buzz would just be at constant volume.
 
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