Lights dimming on brake apply?? [Archive] - GrandAmGT.com Forum

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lastyear4gt
04-07-2005, 08:21 PM
Has anyone noticed the dash and headlights, as well as the blower motor diming when the brakes are applied in 03-04 GA's?? Anyone found a fix for it?

iceman
04-07-2005, 08:23 PM
Possible indication of failing battery/alternator, get them checked out.

If you want to beef up your primary charging wires, underhood fuse block supply wire, and engine grounds, that would help. You can search around for details on that mod.


Mine did it when stock, stopped when I had a yellow top and upgrade wiring.. Now that I'm back to stock, the wiring is still there, no dimming. Basically it's just the momentary current draw from all 7 brake lights lighting up and the brakes engaging... crap happens hehe

SC/TGrandAm
04-07-2005, 08:23 PM
No because thats not normal.

Id start out with having your battery and alternator checked. Under warranty, take it to the dealer and let them jack with it.

Panacea
04-07-2005, 08:26 PM
Does it permanently stay dimmed? Or is it just for a short second? If it's for a short second I would say that it is normal. My car's been doing it since day one. Only cure I'm aware of is getting a bigger alternator.

SC/TGrandAm
04-07-2005, 08:37 PM
hmm,. only time my lights ever dim is when i turn on my rear defrost and thats for a split second.

I will say the delco stock battery is junk, it obviously helps to get a better battery.

Panacea
04-07-2005, 08:47 PM
Happens with my Red Top too. It's the alternator not having enough amperage or something to that affect.

iceman
04-07-2005, 08:50 PM
Upgrade your wiring under the hood, it will go away

ram444
04-07-2005, 10:26 PM
Possible indication of failing battery/alternator, get them checked out.

If you want to beef up your primary charging wires, underhood fuse block supply wire, and engine grounds, that would help. You can search around for details on that mod.


Mine did it when stock, stopped when I had a yellow top and upgrade wiring.. Now that I'm back to stock, the wiring is still there, no dimming. Basically it's just the momentary current draw from all 7 brake lights lighting up and the brakes engaging... crap happens hehe



Agreed, had the same problem. I had to replace my battery. Get a optima dry cell.

lastyear4gt
04-08-2005, 05:05 AM
No because thats not normal.

Id start out with having your battery and alternator checked. Under warranty, take it to the dealer and let them jack with it.

LOL, I work at a dealer, I am a GM tech. I have checked, cleaned and tightened all the grounds. I checked for bulletins, and found one from back in 2001 for a pontiac montanna with the same alternator. The fix was to replace the diode bridge grounding bolt, and still the same thing. I contacted Technical assistance, and they were stumped too, but I have test driven other customers cars overnight before, and they all have the same problem too. Just though maybe someone has found a fix.

I'll try the wiring replacement. Should I just replace the ground straps??

tenspeed
04-08-2005, 06:09 AM
I consider it normal because when you hit the brakes, the tail lights come on and the ABS may be activated. This happens just after you take your foot off the gas so the engine is dropping RPM's.

You're calling for more electrical power at the same time as when your altenator is slowing down so the lights are going to dim a little. The system senses the reduced volts and increases the output of the altenator.

snawdjj
04-08-2005, 06:16 AM
I have an 04 SE, and it shows the same dimming problems. When I get some time I’m going to upgrade the power lead from the alternator to a good 4ga wire. If that does not sort it out I’m thinking of upgrading to a stiffer alternator (which coincidently suggests you upgrade the wire running from your alternator).

Good luck, and I would love to hear what you try to do to fix it.

pico
04-10-2005, 03:23 PM
Mine did that. The interior lights would dim out only for like a split second. I never noticed until I had to get another alternator when the stock went out.
I ended up getting a 160 amp alt (mainly for the dimming from my system) and redid the wiring. Haven't a problem with it since....with, or without my stereo on.

I asked about this same problem a few months ago when I first noticed it, and from what I learned, it's pretty much normal though.