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View Full Version : Need help a with mysteriously occuring Voltage Drop Problem



89HatchbackLxi
01-14-2014, 07:47 PM
Ok, so this last weekend I installed some new HID's I got from DDM tuning onto my 95 SL. The install was easy minus the fact that it took me 45 minutes to get the bulbs out of the ridiculously tight fitting connectors. Anyways, I tested out the lights by driving around the neighborhood for a few minutes and all was well. The lights operated exactly as they should. No problems at all. Well great, sounds like I'm all set then right? Apparently not. Yesterday, on my first actual drive anywhere since installing the lights, I go get gas at costco. it's about 5:30pm, around sunset time, so I turn my lights on. New HIDs operate perfectly on the way there. i sit in park in line at costco and my car idles as it should. Finally get gas after about 10 minutes of waiting in line, start the car, turn on the hids, no problem. Exit the costco lot, all is well. I turn into the street and hit a red light a few seconds later. Upon the light turning green, I take my foot off the brake, and begin my way thru the 8 or so stop lights between costco and my house. Another red light, so I hit the brakes and slow down as usual. Upon hitting the brake, I notice my driver side HID shuts off. Lovely. Switch the lights off and on a few times, no luck. Driver light remains dark. Figure i'll take a look at it when I get home, see if maybe something is lose (although with connections that tight, I'm pretty sure that is not the issue). After driving a little bit, maybe 15-20 seconds later, my driverside HID lights back up. Maybe it is a faulty connection? Another stop light. I Hit the blinker to change lanes, hit the brakes and.... click, driver side HID shuts off. Crappy ballast? Maybe. Green light. Then, 15-20 seconds after accelerating the light again comes back on. I go over a bumpy area of road, light remains on, I look at the built in voltage meter and I realize it's probably not a connection issue, but an alternator problem. The meter is reading exactly 12 when I'm stopped at a light.

By now I'm eying the voltage meter the rest of the way home. After a few more stop lights, the HID now stays on, and the voltage meter goes back up to 13 range. I activate the turn signal to make a turn into my neighborhood? voltage drops to about 12, maybe 11.75 with each turn signal flash. HID stays on though, and after the turn signal disengages, the needle goes back up to about 12.5. I get home, check the HID connections. Everything is connected fine.

A few hours later I decide to do some additional troubleshooting, I drive around the neighborhood for about 20 minutes stopping to allow the car to idle for a few minutes a copule times, while engaging everything but the wipers to throw a load at my alternator. HID lights stay on, and I can't get the needle to drop past 13. What gives? I thought my alternator was bad?

I realized in the past the voltage has went around 12 sometimes when I'm idling but I never thought anything of it since it didn't seem to effect anything until now. I realize I could always just put my halogen bulbs back in, but it seems no one else has problems running HIDs, so I'm gonna keep that as my last option.

I found a thread about the same issue on a different 3000gt forum, and apparently a bunch of people ran into the same situation I'm in with the voltage being picky but only sometimes, not constantly, but there was never a solution found, and it was a thread from 4 years ago, so I was hoping maybe someone has figured out a solution by now...

89HatchbackLxi
01-14-2014, 08:06 PM
One other alternative fix I'm thinking might work is maybe if I switch all my other exterior lights to LED (tail, brake, fog, turn, etc), this would maybe draw a lot less power, or at least just enough to not drop the car under 12 volts so my HIDs don't shut off. Or would that not help?

wingnut
01-14-2014, 08:42 PM
Im gonna go with Voltage Regulator failing, its part of the alternator.

89HatchbackLxi
01-14-2014, 08:52 PM
I guess... Could it be failing for over a year though? And it's just weird that it only happens when the headlights are on... As far as I know the car has been this way since I bought it in 2012, it's just never effected anything important until I put HIDs in. Halogens just dim when there's less power, HIDs just go dark, which obviously isn't good.

stealthee
01-14-2014, 09:34 PM
Headlights could be putting just enough draw on it to where the alternator can't keep up.

89HatchbackLxi
01-14-2014, 10:24 PM
That's what I was thinking, but I did more test driving tonight, and I could get the Voltage to go down to 11 with the brights, turn signal, brakes and rear defrost on while idling, but this time, the HIDs stayed on... I don't get it. Shouldn't HIDs be using less power than halogen bulbs though?

wingnut
01-15-2014, 12:45 AM
Stop guessing...Bring car to local parts store...test alternator :wink:

95gto
01-15-2014, 09:17 AM
I would suggest upgrading the feed wire from the battery to the fusible link. The stock wire is pretty small, 10ga I think, so adding an 8ga wire is a good idea if you think voltage drop is an issue.

89HatchbackLxi
01-15-2014, 01:24 PM
Stop guessing...Bring car to local parts store...test alternator :wink:

I'd like to, but for some reason the part stores around here in CA don't do that anymore? Something about California.


I would suggest upgrading the feed wire from the battery to the fusible link. The stock wire is pretty small, 10ga I think, so adding an 8ga wire is a good idea if you think voltage drop is an issue.

Hmm... Sounds simple enough. Thanks, I might try this.

wingnut
01-15-2014, 01:40 PM
I'd like to, but for some reason the part stores around here in CA don't do that anymore? Something about California.

Sure they do...autozone. I lived in norcal for a few years, had mine tested there more than once!

Jimvr4
01-15-2014, 02:05 PM
Yeah I think AZ can do it.

Do you have ABS? It's another big drain on a weak electrical system. I once found out the car can't run on the alternator alone when ABS is operating.

89HatchbackLxi
01-16-2014, 05:00 PM
Sure they do...autozone. I lived in norcal for a few years, had mine tested there more than once!

Recently? They wouldn't even check my girlfriend's corolla engine code, that was about 6 months ago.....

89HatchbackLxi
01-16-2014, 05:04 PM
Yeah I think AZ can do it.

Do you have ABS? It's another big drain on a weak electrical system. I once found out the car can't run on the alternator alone when ABS is operating.

Hmm ok. I might go in and ask then. Maybe it's only engine codes they don't check here. And yes, I do have ABS. Makes my car lurch if I hit the accelerator before it runs it's self check, lol.

My driverside light went out this morning when backing out of my driveway, Voltage was at 14v. Maybe it IS a faulty ballast?

Edit: upon further troubleshooting I found that it WAS a defective ballast. Appears to be a loose solder connection or something inside the ballast. Thanks for the help guys, but I think my car's weird voltage isn't really a problem after all. Not yet at least, lol.

Streamln1
01-18-2014, 08:45 AM
There are a lot of hid kits that have these problems. They are just made cheaply