Lights dim when i hit the brakes.

[plaaya69]

I know I seen 130 Amp alternators for our cars but I have yet to see someone with one in their Supra.

 

[jetjock]

Isn't the MkIII alternator also somewhat underpowered to start with?

No, because it's job is not to power the electrical system. That task falls to the battery.

 

[iwannadie]

did you even pull the fuses inside the car in the kick panel? just thought with all those fuses so close to the battery you might have forgotten the rest...


I have this slight dimming when i change the voltage needed from the electronics, but yes it's usually coming home at night when i apply my brakes. I notice it more when my wipers are on but i usually always run with fogs on when my headlights are on. so that means what, 9 bulbs are going? the voltage doesn't come back up too quick but it's not horrible or that much of a dip. i notice the voltmeter twitch when i use my hazards. not sure about the blinker.

Yea, I pulled the fuses inside the car too 1 at a time, no drop on my multi meter.

 

[86Supraguy]

its not the alternator its the kind of bulbs you have back there and how much power they drain. mine did the same thing.

 

[boostinboy]

Somtimes the wrong bulbs can cause this. i know someone this happend to the wrong bulb was put in to the taillight and caused the lights to dim when the brake was hit.
also check your fuses too

 

[cuel]

I've had problems with the grounds in the tail light housings coming loose, but that usually kills the tail/brake lights.

I use a larger battery than stock, and the alternator off an auto. 89 turbo. Iirc, it has a little higher output, and is able to keep a better charge on the battery. I have dual electric fans(pull 20 amps on low, 30 on high), 300 watt amp, and after market 65 watt driving lights. With everything else running(radio on, headlights, wipers, and driving lights), I see a slight drop(2 volts) on the stock gauge when I turn the a/c on(high fans kick on with the a/c pressure switch) high. Looking at getting an Optima soon, as I'm gonna be adding more electronics. I'm also gonna switch back to the clutch fan, as I think these are keeping the radiator too cool. Plus they're off a Ford, and will probably leave me stranded... :biglaugh:

BD: Not sure what you need to do to fix your problem, but I would get a better battery, as you said its smaller than stock.