Last night I noticed my headlights and dash lights dimming when I hit the brakes. Is my alternator or battery going out? I didnt have the AC on and it did it even when I turned off the stereo. Which also dimmed the lights when the bass hit. WTF

 

Alternator

 

yes either your alternator is dying or not charging

 

It could be the alternator, but first you should have the electrical system checked out for shorts. I had the same thing - turned out to be a short. Took my mechanic an hour to trace & fix - never had the problem again.

 

bad ground? maybe a dual phase bulb in a single phase light?

 

It could also be your battery. trust me I know from experience. Test the battery voltage with the car off first.With the car running, diconnect it, and if the car shuts off, its the alternator. If not its your battery. I know some may disagree, but After two bad batteries, it was proven.....

 

Could u please elaborate more on this procedure, my lights dim when i hit my window switches. ( i have a red top, and those Silvania silverstar headlight bulbs)

 

wow... i'm having the same problem as you too. it is more noticable when i am at a stop. i noticed it when my windows are already rolled up and i 'try' to roll them up any more, i can see my headlights dim a little and it gets dimmer for every window i try at the same time (ie: 2 windows at once or 4 windows at once.)

 

If they don't dim much, it should be just normal operation. it's more noticable to me after getting my UDP installed but it has always done it slightly. Just be glad you don't own a pontiac grand-am they do it much worse.

 

thanks , i'll try it

 

Grounding kit might help

 

My 96 GLE had the same issue several years ago. When braking, the lights and stereo would blink off for a split second just as the brake was depressed.

Turned out to be a short in a taillight (brake light I think). Drove me and several mechanics crazy trying to figure out for months. Once the short was fixed, no problem ever....

 

hehehehe Every since I upgraded to PIAA Extreme White Plus's, whenever I turn the lights on, engine rpm's go up a bit. Act's very similar to turning on the A/C. Must be a hell of a draw!