Lights dim for a second

[canadian_ice]

Whenever I press the brakes now, my front lights dim for about a second, and then go back to normal. What could the problem be? I recently installed side markers, fogs and washer lights, but none are connected to the same wire as the headlights/brakelights. (fogs/side markers are on a switch, washer lights connect to turns)<P>Is this something I can fix, or should I take it to my local shop?<P>THANKS!

[Maddbuck]

Questions: <BR>1. does it only do this when the side/fogs are on ? <BR>2. Did it do it before the mods?<P>one thing is the RS models of the MX-3 are prone to this headlight dimming thing. My old RS used to do this when the A/C used to kick in. Sorry but can't help much more than that.

[jfbourgault]

my gs does the same, but it's a very light dimming of the lights that I get, I think it might be your alternator or something on the charge system!

[canadian_ice]

Hi,<P>It does it without the fogs on and I'm not 100% sure about before, but I don't think it did it. I never really noticed. I don't think there's anything wrong with the alternator, but it goes in for a service next month so I'll get them to check it out.<P>It's only a slight dimming...am I just drawing too much power with my lights? I hope not - I want to put subs and some neon tubes in this summer.

[OctaneChicken]

Since you added the fog lights it acts as a load and when you press the brakes, the brake lights need to draw a large initial current (light bulb acts as a short) to turn on the brake lights. This will cause the current in all the other circuits of the car to go down (since current tries to find the easiest way to ground) until the current to the brake bulbs have stablized. As you know if you add more stuff to the car (ie amp, fog lights...) the more current you will need.

[tk1138]

Is the light dimming synchronis with the slight drop in RPM that occurs when you press the brakes? If so then you probably could use a bigger alternator like almost everyone with an electrically modified mx-3. Whene you press on the brake pedal the brake system has to work harder, and this causes a reduction in RPMs due to the mechanical load. the ECU compensates for this by increasing the RPMs, but it's not instantanious. The electrical load of the brakelight is small compared to the mechanical load of the brake system, but in either case, a bigger alt wil help by reducing the amount of energy the battery needs to supplement the system by. The stock one will probably work OK, but if you want really steady lights, then you'll have to upgrade it, and maybe get a Cap, or dry cell battery. Check out the discusion in the stereo/alarm section.