I searched the electronics forum, and did not find anything on this, so, I thought I would ask everyone. I did see a tech. article relating to this, but, didn't know how to get ahold of the person; i am somewhat new on this place.
What i wanted to know is how to modify the wiring for the headlights and how to wire up a manual fan switch.
I have the fan swith wired up straight to the battery through an external fuse; my question is, every time I turn on the switch, the headlights and interior lights dim a little bit. I love wiring, but, don't know enough about it; i am assuming that I am supposed to add a relay in to the wiring to eliminate the dimming of the lights every time I turn on the switch.
I also wanted to know if using relay's on re-wiring the headlights up to the battery, if it gets rid of the dimming of the interior lights when you turn the headlights on?!
Thank you ahead for anyone that can help me with this!

 

I would recommend that instead of wiring the fan switch straight to the battery, you wire it to the ignition switch - that way if you forget it on, you won't run the fan until the battery is completely dead.

As for the dimming, they dim because there is additional load on the electrical system that wasn't there before, which has caused the voltage to drop a little bit.

Adding a relay to turn on/off your electric fan will not prevent the lights from dimming when you turn it on. Some people put headlight relays in place, which reduce resistance thru the wiring harness between battery and headlights (instead of going from battery to dash to headlights, they go straight from battery to headlights). This isn't really recommended unless you have noticeable dimming of your headlights due to old wiring harness. This will also not affect the interior lights dimming, at least not a noticeable amount.

What WILL influence the amount of dimming in the interior lights and headlights is upgraing to a higher amp output alternator, and/or a newer battery (if the one in the car is old and on its way out).

 

Wiring it to the ignition switch will work for the summer. But once you get into weather below 50* it won't be so good. You do not even need your fan on while cruising on the open road.

You really need a relay for your fan. I would not trust a fuse forever. Is your fan wired on the same circut as your interior lights? If so just putting it on a seperate power wire may solve your problem.

 

Is this a factory fan or an aftermarket add-on? If it's factory, you just have to find the ground wire that triggers the fan relay and run a ground switch to it for manual control. If it's aftermarket, definitely hook up a relay for it.

 

He meant wire the fan switch up to the ignition switch.

 

got ya.

 

Thank you all for your prompt replies:
It is a replacement fan to the original dual fan setup. I will eventually hook my dualies back up hopefully....gotta find em in my garage.
This is what happened: The fan was wired on a relay, and in coordination with the, i believe 180 degree, temp. sensor in the engine block. The temp. sensor went south on me, and, being that I was just about to head off to college, I took the easy route and eliminated the relay and temp. sensor, and wired it into a toggle switch.
The wiring goes directly to the battery itself, to the switch, then from the switch to the fuse panel, then from the switch to the fan. I used, obviously, a heavy gauge wire, and I believe a 30 or 35 amp fuse.
So, i don't know how to wire in a relay; but, come the end of school, i will prolly get a new temp. sensor, and re-install the relay; though, I will need y'all's help if I can get it, as, silly me, I can't remember how the relay was wired.
But, it sucks having the lights noticeably dim when I turn the fan switch on...
So, the alternator is new, but, higher output alt.'s are pricey, and, i have a pretty hefty battery.
Is there any other alternatives for adding power??
What about capacitor's?? Can you possibly use those for something other than a stereo system....which, i have not done (yet)....
Thanks again!

 

Capacitors are good for rapid current discharge, but over time they aren't very good for holding power (which is why we use batteries and not capacitors to start our cars).

Aside from a bigger alternator and a bigger (think marine deep-cycle) battery, you don't really have any alternatives to increase power, however you could get more efficient accessories (think running one fan on the dual fan setup if both aren't needed) which will help some, but really doesn't address the main problem - that your alt isn't putting out enough to support all the cars systems.

That said, "heft" has little to do with an alternator's output. The stock 63 amp externally regulated alt on my truck is bigger than the 105 amp internally regulated alt that I replaced the old one with.