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Why are my lights dimming?


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OP word of advice. IF you decide to run a mechman pay the 75 bucks extra for the adjustable voltage version lol i didnt get it on my first H/O alt (irraggi) and i i hated it. now i have my mech man and i amp alot happier. stable voltage

If the alt is bad then I will bite the bullet and get a HO alt like I planned on doing anyway. but this adjustable voltage... I don't know much about alts. does it let you choose if you're running a 14.4 or 16v system?
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no. see your car is pcm controled meaning your pcm decides what your chargeing voltage will be. mine would go between 13.2 - 15.0 and everywhere in between just diving down the road with everything off. it just picked its own voltage. which is no good if u are driving around at 13.3 and turn your system up haha. the adjustable voltage harnes lets u set your voltage at say 14.8 and it will be between 14.8 all the time. not taking into account for voltage drop. so basicly more voltage all the time. and if you wanted to run 16 or 18 volt systems you just turn the dial and voltage will go up. (DO NOT DO THAT UNLESS YOU KNOW WHAT IT WILL TAKE TO RUN !^ OR !* VOLT SYSTEMS)

2002 ford focus hatch

pioneer DEH-P8400bh

infinity kappa 6.5 components front and rear

XS Power D1200

Shuriken BT-100

audioque 120.4

2 15 inch audioque HDC3 D2

2 audioque 2200d

big 3

mechman 220a alt with external regulator

479-418-3056

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no. see your car is pcm controled meaning your pcm decides what your chargeing voltage will be. mine would go between 13.2 - 15.0 and everywhere in between just diving down the road with everything off. it just picked its own voltage. which is no good if u are driving around at 13.3 and turn your system up haha. the adjustable voltage harnes lets u set your voltage at say 14.8 and it will be between 14.8 all the time. not taking into account for voltage drop. so basicly more voltage all the time. and if you wanted to run 16 or 18 volt systems you just turn the dial and voltage will go up. (DO NOT DO THAT UNLESS YOU KNOW WHAT IT WILL TAKE TO RUN !^ OR !* VOLT SYSTEMS)

I don't plan on running a 16 or 18v system. I'm not running enough power to do that. I'm just getting an SAZ-1500D to power my sub. Thanks for that advice, is the PCM usually a part of the alt?
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no the pcm is the cars computer. the harness im talking about will bypass the computer. your battery light will come on but all u have to do is pull out the gauges and take that light out

2002 ford focus hatch

pioneer DEH-P8400bh

infinity kappa 6.5 components front and rear

XS Power D1200

Shuriken BT-100

audioque 120.4

2 15 inch audioque HDC3 D2

2 audioque 2200d

big 3

mechman 220a alt with external regulator

479-418-3056

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no the pcm is the cars computer. the harness im talking about will bypass the computer. your battery light will come on but all u have to do is pull out the gauges and take that light out

lol, I like that idea. I'm constantly learning more on this forum. Thanks for all your help and recommendations. I'll DEFINITELY get the pcm bypass for sure when I upgrade alts
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My envoy does the same thing with my inside lights and if you conentrate enough the dash lights all through the vehicle. The exterior lights are just fine and since i have HID's they dont change brightness with voltage changes. It had this start after i put my h/o alt in my truck and i have put new belts on, new pulley's, new tensioners, etc but it didnt help. It only shows that flicker like you have with your inside light in the video when i am at idle and turn on my dome lights. Its strange because when i hook up my old DMM and even my new o-scope to the power it stays steady at 14.8 depending on the temperature of the engine and alternator and when that flickering occurs i only have a voltage change of 1/10th of a volt (.1v) so its strange that i get that flickering but my o-scope shows no ripple current or big changes in voltages so idk why mine started that after i put my alternator in.

Did you measure your voltages at the battery when this occurs just to see if its jumping a lot during that flickering stage? I really dont think its a bad alt because when i put a high load on my alt it still performs just like a champ and puts out way more than 270 amps which it is rated for but at idle with the only load on the electrical being of the stock electronics and engine it makes no sense to see that flickering.

A little side note would be to check the ground wires and power wires for resistance in your system. My sisters old car had a huge jump in voltage no matter what rpm the engine was at and it was just from a dirty ground bolt on the engine block and unibody. I cleaned it up and it was fine once i got the resistance in the line down to .01 ohms.

2004 GMC Envoy1 XS power S3400 batt under the hood and 4 XS Power D3100's battery installed in the rear by the amps0 gauge power wire from front to backAlpine iva-w205 touchscreen dvd/cd/mp3/ipod/am/fm/gps headunitSundown Audio SAX-200.4 amp for my mids and highs8 gauge speaker wire from amp to woofer270 amp Mechman AltRockford Fosgate T1652-s component speakersRockford Fosgate 3Sixty.2 sound processorRca's from Rockford Fosgate and Monster Cable14 gauge speaker wire for the mids and highs1 18" Ascendant Audio SMD Dual 1 ohm with custom Black & Blue carbon fiber and hand signed dustcapBox: 5.66 cubic feet net volume box tuned to 30.13Hz with 1.5" wide wooden dowels and 1.5" thick baffle1 DC Audio 5.0k amp wired to .5 ohms nominal with an imp rise of 1.35 ohms for the single AA SMD 18"Future Vision 8000k 50w bi-xenon projector HID's with 4300k 35w fog lightsLink to my build: Buildupdates/progress

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I hooked up my DMM to te battery and I saw voltage dropping down to 10 and 11 volts when revving the engine. I'm going to do some tests and try unhooking the big 3 and see if that helps at all. I hooked up my larger marine grade battery and I saw improvements but I think that might have been because it was a larger and newer battery

Edit: as for grounds, I did the big 3 but I need to make the ground on the block better. Ground on the chassis was done pretty well with a wire brush attachment and a power drill

Edited by Crandis16
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I hooked up my DMM to te battery and I saw voltage dropping down to 10 and 11 volts when revving the engine. I'm going to do some tests and try unhooking the big 3 and see if that helps at all. I hooked up my larger marine grade battery and I saw improvements but I think that might have been because it was a larger and newer battery

Edit: as for grounds, I did the big 3 but I need to make the ground on the block better. Ground on the chassis was done pretty well with a wire brush attachment and a power drill

your alt is bad, or already has a failing part in it. the big 3 NEVER EVER EVER harms anything, so you'd just be wasting your time unhooking it. fixing the ground will probably not help, but its good to have the best conductivity possible.

your lights flickering while the car is on with virtually NO loads on the alt, means that the alt is bad. you could probably just unplug/unhook the alt and the flickering would stop

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Where does your voltage rest at when you leave the vehicle off for a few hours? Id toss a battery charger on your batteries since it sounds like you are really killing the batteries getting run down that low, i ran my truck without my alt engaged and had it at 12.4v with just my s3400 under the hood. Charge up your batteries, remove the charger, let them sit there for like 4 hours and take a voltage reading. Also if you have a buddies car to use take your alternator off and run down to somewhere like advance auto, orieleys (sp?) or any other automotive parts store that can test alternators in store and see what the test comes back at.

2004 GMC Envoy1 XS power S3400 batt under the hood and 4 XS Power D3100's battery installed in the rear by the amps0 gauge power wire from front to backAlpine iva-w205 touchscreen dvd/cd/mp3/ipod/am/fm/gps headunitSundown Audio SAX-200.4 amp for my mids and highs8 gauge speaker wire from amp to woofer270 amp Mechman AltRockford Fosgate T1652-s component speakersRockford Fosgate 3Sixty.2 sound processorRca's from Rockford Fosgate and Monster Cable14 gauge speaker wire for the mids and highs1 18" Ascendant Audio SMD Dual 1 ohm with custom Black & Blue carbon fiber and hand signed dustcapBox: 5.66 cubic feet net volume box tuned to 30.13Hz with 1.5" wide wooden dowels and 1.5" thick baffle1 DC Audio 5.0k amp wired to .5 ohms nominal with an imp rise of 1.35 ohms for the single AA SMD 18"Future Vision 8000k 50w bi-xenon projector HID's with 4300k 35w fog lightsLink to my build: Buildupdates/progress

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Where does your voltage rest at when you leave the vehicle off for a few hours? Id toss a battery charger on your batteries since it sounds like you are really killing the batteries getting run down that low, i ran my truck without my alt engaged and had it at 12.4v with just my s3400 under the hood. Charge up your batteries, remove the charger, let them sit there for like 4 hours and take a voltage reading. Also if you have a buddies car to use take your alternator off and run down to somewhere like advance auto, orieleys (sp?) or any other automotive parts store that can test alternators in store and see what the test comes back at.

x2 the bolded part. i bet that 13.8v reading you got from your battery was probably right after you shut the car off. you have to wait a long while to measure the battery voltage so it can get rid of the surface charge created by the alternator charging it.

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