Brute03

i noticed last night when i roll my windows up, all the lights dim (inside and out) and the idle dips a few hundred rpm. the lights alsogo dim for a second when the a/c cuts in.so i tried to duplicate it in my g/f's Fontier and nothing happed.

Now my alternator is less than a year old and it puts out over 14 volts, so i don't think that it's the problem. could it be abad groundor the battery getting ready to take adump?

Quick Shot xMLx

I don't have such a noticable problem, but often times when I'm rolling the windows up especially if I hold the button when they are already up the lights dim ever so slightly and the rpm drops like -100. Kind of the same thing you're going with, car has being like that for over a year now no problems with the battery/alternator.

lizzyfan

Alt is gonna take a dump

Whamo

^not totaly true, the drain on your battery makes the alternator "kick it up a notch" so it makes more power by putting a bigger load on your engine.a bad battery needs mroe power. i would replace the battery with a yellow top and call it a day.

Brute03

like i said, the alt is practicaly new, but i don't know about he battery, it's not Motorcraft andit's a little beat upplus i killed it twice when i was doing some work on my system [X(]

quitbichyn

i was having the same problems plus my stereo would shut off randomly while i was driving. also had some problems starting the car..but did i mention that i have 2 JL 12W6 subs and a 1400watt amp??

solution: bought a optima yellow top battery and a cap for the system

so...+1 on the yellow top. those things are effing amazing!!!

bighedmick

Try load testing the battery and see what it does. Is it a Ford alt. or a cheap p.o.s.? I've replaced alternators that are crap right out of the box.After I changed my pulley's I noticed a slight dip in voltage as well.

Jbauer

from my experience (especially with VW at work, and my personal mustang) All cars do this..no stock alternator i've seen has the capacity to have both window switches depressed at the same after the windows have rolled up. the RPM will dip down a bit and the lights will also dim..
EDIT: never mind.. it shouldnt dim and drop RPM when the AC comes on, or WHILE your rolling up the windows

Whamo

not to thred jack but what kind of spl do you have??

bighedmick

No, your right. You will notice a slight dip in rpm's (100 or less, give or take) if you are trying to operate multiple components at the same time. Generally all vehicle's have some kind of ELD, or electronic load detection to correct or assist in any increased amount of load. Pretty brave admitting that you are a VW tech. I too am a tech of a different brand but I choose not reveile this information at this time due fear of ridicule.