Help...Dimming Headlights

[Odin8]

Well guys, here I go on a semi brief run down...if you need to hear more info to make a better judgement just ask me and I'll tell you if I know it. I'm getting aggravated and I'm looking for some input here. My car has been tested with 3 different alternators and 3 different batteries in the past week, and no matter what I do my headlights dim when my bass hits. Running about 1500 watt system, all cable is 0 gauge, have a Batcap 400 for a backup battery/capacitor, and one of the alternators used was 250+ amp output.

Take my radio out of the question and the car performs beautifully right now, has a brand new stock alternator in there, I get 14.2-14.7 going down the street, and I'll come down to about 13.2 at a stop under full load (high beams, heater, heated seats, etc). Turn my radio on, and my lights dim when the subs hit. Doesn’t matter what I’m doing, I can be going down the road reading 14.5 volts, and my lights will still dim. And I mean everything in the car will dim as well, not just my headlights…my dash will dim, my vanity lights will dim if they’re on, along with anything else inside or out. All my connections/grounds for the stereo, battery and alternator have been tested numerous times, I'm not getting any voltage drop anywhere, and the batcap was tested and good.

My latest suggestion is to upgrade to a bigger capacitor, but the sound place I went to said he wouldn’t guarantee that’d fix the problem, and said that the one I have should be more then enough for my system anyways. He's pretty stumped, and wants me to go to a different shop to get another charging system test done, says it seems like the car is putting out great voltage but is lacking amperage somewhere.

I need some ideas here. Anyone got anything? After it was installed and even after my alternator was replaced the first time, I never got dimming headlights. System was done about 6 months ago; alternator for the first time was done about 2 months ago. My dimming problem started about a month ago. So seemingly the dimming problem is independent of any changes being made to the car. Help me, please. This is driving me crazy.

[dp102288]

It may not help, but this is the only thing I remember that is applicable to your dimming...

http://www.cadillacforums.com/forums...-thinking.html (BIG 3 Upgrade (A must for anybody thinking about a system))

[Odin8]

Yah I already did that, but thanks.

All my cables are 0 gauge. From battery to chassis, alternator to battery, and battery to block. Along with all the stereo cables.

[Odin8]

Tried a new battery today and didn't change anything. Still have the brand new stock alternator in there. Any ideas? I'm going crazy. And anytime a load is put on the car, my lights will dim. Take my stereo completely out of the question. If I'm sitting at idle and tap the brakes, my lights will dim.

[dkozloski]

You're looking at a bad cable connection, either battery or ground. Pull them all apart one by one and clean them up. Put some corrosion proofer on them before you button them back up. You've got at least one that got wet and has corroded.

[Rag64top]

I'll be interested to know what your fix is, I have the same issue with my 99 Eldo, not the stereo thing, but my headlights dim whem I hit the brakes.

Rags

[harold4]

My 98 eldo's headlights dim when I hit the brakes, as well. Did you find the cause of this?

[ltsjr]

same thing 96 sls whats the deal?tap brakes lights dim blower fan slows also.thanks guys.

[01devilledts]

You defiantly need a large capacitor, im running 2 300farad caps and i still have a small amount of headlight dim, the one thing you can do is run a separate battery for your stereo. that will take the stereo off the same circuit as the rest of the car.

[ltsjr]

well here was my cure . took it to the shop,put it on the computer ,voltage regulator in side alternator was bad .it was cheeper to replace the whole thing than to rebuild it .bought a new battery too, it was the one that came from the factory,that was comming any way.works great .good luck guys.