Question about 2007 Pontiac G5 Gt Coupe

3 Answers

Headlights flash with bass

I have a 2009 Pontiac G5 GT with aftermarket subwoofers, 2-12inch subs. So when I have the bass on loud the indash lights, mirror lights, and even headlights flash when the bass pounds. The subs are in the trunk and in this model so is the battery. The subs are hooked up to their own amp, and my stereo guy has assured me they are wired in properly.

Is this bad for the car? I have had the car for about 2months but have only noticed this issue in the last day or so. Should I be worried and get the car checked out?

Thanks for the replies....

Posted by on

  • 2 more comments 
  • Abel003 Dec 08, 2008

    Thanks for the reply, that is definetely the problem. I have been reading on other forums saying I should buy a capacitor to help out.....

    Is that a good way to go? Or should I just buy a more powerful alternator....

    What are the price costs here?

  • Abel003 Dec 09, 2008

    Thanks wiz.....I am looking into buying a higher output alternator now.

    My stereo amp puts is 1000watts....and my stock alternator is 105amps....Will 130amp alternator be ok...or should I get higher like 140? or higher?

  • Anonymous Dec 19, 2008

    I decided to not put anything in. It is a brand new car, and GM's highest alternator they do is in there right now. If I put an aftermarket alternator in my entire warranty is void, so I am not going that way. I am not going to put a cap in either....cause it may not solve the problem either.

    I'm just going to keep a manual eye on it.... I am just hoping that it doesnt wear out my alternator that much quicker. If it doesnt affect the car too much than I am not going to worry about too much.

    I am not sure what class my amp is. The battery is brand new, brand new stock GM battery. I assume it was at full charge when I got it. I bought it at the end of October.

  • Lanc5r01 Apr 14, 2009

    I have a 01 lancer and have this same problem, i only have a 10 inch sub and its wired perfect, i was told at an car audio joint that my sub might have a short but not sure how to check that, might be time for a new amp.



3 Answers

  • Level 1:

    An expert who has achieved level 1.

    New Friend:

    An expert that has 1 follower.

  • Contributor
  • 1 Answer

Look into a capacitor for your amp.

Posted on Jun 24, 2013

  • Level 1:

    An expert who has achieved level 1.


    An expert that has over 10 points.


    An expert whose answer got voted for 2 times.

    Problem Solver:

    An expert who has answered 5 questions.

  • Contributor
  • 16 Answers

So your lights flash. big deal. I have seen alot of guys get bigger alternators and stiffening caps. the battery in the trunk.. very nice.
seriously i think it might not be a simple one fix answer.. higher amp alternator may have higher cut in rate. you may need to rev higher to get the juice. are you using a d-class amp or a wasteful a-b class. you must have heavy wiring and in short lengths i hope.
what kind of battery do you have? when was the last time it was full charged.

throw on a charger if you have a decent battery. - optima.. or anything high amperage.. the battery is important the alternator should be ok.

look into a low cut in alternator. even of the same amperage

Posted on Dec 19, 2008

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points

    Top Expert:

    An expert who has finished #1 on the weekly Top 10 Fixya Experts Leaderboard.


    An expert that got 20 achievements.


    An expert that got 10 achievements.

  • Pontiac Master
  • 78,267 Answers

The sound system is exceeding the capacity of the Alternator, it takes allot of power to run the subwoofers, they make higher output alternators for just this situation, u will need one with at least 130 Amps output.

Posted on Dec 08, 2008

  • yadayada
    yadayada Dec 08, 2008

    It is the only option you have, u are most likely talking about $200-300


1 Suggested Answer

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

A 6ya expert can help you resolve that issue over the phone in a minute or two.
Best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
The service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.
Good luck!

Posted on Jan 02, 2017

Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

1 Answer

Power steering failed in my 2007 pontiac gt, during extreme cold?

Have you checked to see if its under recall? They released one for power steering back in 2009 I believe.

Feb 22, 2015 | 2007 Pontiac G5 Gt Coupe

1 Answer

Previous owner of my 2009 pontiac g5

Call or go to any GM dealership with the VIN number and they can check.

Jan 31, 2015 | 2009 Pontiac G6 GT

1 Answer

How do I find the backup light switch for a 2009 Pontiac g5 automatic transmission

The "back-up Reverse light switch I believe is incorporated in the gear shift selector Dash or console mounted?

Dec 14, 2014 | 2009 Pontiac G5

1 Answer

Signal light switch on 2007 pontiac g5 does not turn off

The multifunction switch may have to be replaced.

Nov 24, 2017 | 2007 Pontiac G5 Gt Coupe

1 Answer

I just installed a JVC aftermarket Stereo in my 09 G5, and no sound comes out of the speakers at all, and when i start my car and turn on the stereo, my gauges go completely retarded... i know i hooked it...

You may wish to check to see if your g5 is equipt with a external amp where the radio and amp are two seperate parts, if so you may not be giving power to the amp which can cause no sound.

Feb 24, 2011 | 2009 Pontiac G5

1 Answer

How hard is it to change a bulb on the headlight of a pontiac g5

Look in your owner's manual. They'll tell you which bulbs to buy and how to replace one.
It's a very simple procedure. Lift up your hood and look at your headlights. You can see the connector on the back of the headlight.

Jan 19, 2011 | 2007 Pontiac G5 Gt Coupe

3 Answers

I want to add cruise control to a 2009 Pontiac G5 with the manual transmission. My dealer wants to add an aftermarket unit that fastens to the side of steering wheel. Do I have to settle for this or can...

you will require a new steering wheel.
and it is almost $500 from the dealer.
It will look like this...

The aftermarket one does not stick off the handgrips of the steering wheel - it is on the bottom Hub area.

The aftermarket uses a wireless transponder and the brain is hard-wired into the ECU (computer)

Im not sure that your vehicle has the existing wires in the harness to facilitate adding a cruise in the steering wheel without replacing the entire steering column... or wiring harness.

Im sure with the right amount of $$ it can be done - but the aftermarket one is the least invasive and cheapest route for you.

All the cars... cobalt, g5, g6, g7 etc... have the cruise control built in the ECU, and it simply needs to be turned on using the GM Tech Tool Candi II. Its the part about switching it on and off that the costs are involved.

Go with the aftermarket - its really not that bad!

Thanks for using FixYa - a FixYa rating is appreciated for answering your FREE question.

May 14, 2009 | 2009 Pontiac G5

1 Answer

Head lights flash when bass hits

your battery and/or charging system isnt strong enough to handle the load the 15" subwoofer is causing.

you will need to add a capacitor to your audio system.

Feb 28, 2009 | 2007 Pontiac G5 Gt Coupe

Not finding what you are looking for?
2007 Pontiac G5 Gt Coupe Logo

387 people viewed this question

Ask a Question

Usually answered in minutes!

Top Pontiac Experts


Level 3 Expert

78267 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22326 Answers

Jeffrey Turcotte
Jeffrey Turcotte

Level 3 Expert

8836 Answers

Are you a Pontiac Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides