2004 Pontiac Grand Am Power Loss when Brakes Pressed

Tiny
SEAMAJ
  • MEMBER
  • 2004 PONTIAC GRAND AM
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 74,000 MILES
Car starts fine, engine sounds good, but when the brake is pressed, you can see the lights dim inside and outside, as well as when the heater is running, it reduces. Everything seems to power back up when gas is pressed.
My assumption at first was battery, but the car has no problems starting. My second guess is the alternator.
This is the SE2 edition.

Thanks
Friday, February 20th, 2009 AT 10:25 AM

3 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,640 POSTS
Hi:
A slight dim is normal when added draw is placed on the system. However, if you feel it is excessive, I would have the alt checked to make sure it is producing the required voltage and there isn't a problem with the voltage regulator.

Many parts stores will check it for free, so there shouldn't be any out of pocket expense.

Let me know what you find or if you have other questions.

Joe
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Wednesday, February 25th, 2009 AT 11:13 AM
Tiny
SEAMAJ
  • MEMBER
  • 2 POSTS
After taking it back to the dealer where I got it from, they said that the battery and alt needed to be replaced. As far as I could tell, just the battery was replaced, not the alt. The car still does it, and it is very excessive, to the point even when a turning signal is on, everything dims and the heater pauses. They told me that the battery just needed some charge up time and it should stop, but to no avail.
I am pretty sure that if they replaced the alt, that it would have solved the problem, but I think they do not want to do it.

Thanks for the info.
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Wednesday, March 4th, 2009 AT 9:07 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,640 POSTS
Unless the battery is very low, the problem will not solve itself. It is either a bad ground or a bad voltage regulator.
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Wednesday, March 4th, 2009 AT 10:21 AM

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