rome99LS

Ok, just replaced battery a week ago, changed altenator back in january. Now the battery light and headlight leveling came on at the sametime. I turned it off and turned it right back on and seemed just fine. I do have HIDs stock. And the A/c is running fine. Besides those lights evrythingelse seems fine.
When I turned it off and turned it back on at idle the battery light is only on. But when I put it in gear togo foward and press the gas the headlight leveling comes on asap. Can u guys help me figure this out please?

Thank you in advance.

cobalt91

check the cables on the battery and all the connections on the alternator. Sounds like a loose wire to me.

parkerjs

Another possibility could be the headlight leveling motor binding in one of your headlights and loading the battery.

Do the headlights move smoothly to register when you initially start the car and exhibit the problem?

PureDrifter

iTrader: (10)

please read up on the difference between current and amperage. besides the battery isnt used as much more than a giant cap since the alternator provides all electrical power for when the engine is running.

cobalt91

Sorry. Trying to help point op in direction of the problems with his car. As he replaced battery and alternater seems like a good place to start.

rome99LS

So wat are u suggesting PD? How does the headlight motor look and is it around the headlight housing??

parkerjs

It's a legitimate theory and here's how it works.

A motor presents an inductive load to a power source (battery, alternator or whatever it is) and that load is intially very high until the motor begins turning and the counter emf in the windings develop an impedance that reduces the current demand. The motor winding is really nothing more than a piece of wire and is initially a direct short across the terminals of the power source and attempts to drive the voltage across those terminals to zero. That's why lights will often dim briefly when an inductive load is energized and a power source is weak.

Under normal circumstances the motor turns, a large impedance develops as the shaft speed increases, and the current demand on the power source decreases, but if the shaft is not able to turn freely because of mechanical drag, the impedance stays low, the current demand on the power source remains high, the voltage across the terminals of the power source goes down. If the voltage goes down and stays down below the threshold to trigger the battery light, the battery light will come on and stay on for as long as that condiction exists. If sometimes the motor shaft drags and sometimes it doesn't, the problem will come and go.

May not be the problem, but it's a legitimate theory based on a full and complete understanding of the physics involved. Flog me if you must for referring to the battery instead of the electrical system because you're absolutely right.... when the engine is running the alternator powers all systems.

If the problem isn't found elsewhere, I would recommend you check for mechanical drag on the headlight motors when they cycle through their motion when initially turned on. I'd also recommend removing the motor from the headlight housing whild leaving it electrically connected to see if the problem can be created with no mechanical load on the motors.

If the problem still exists, move on to the next theory. Just trying to help generate legitimate theories to help the cause.

parkerjs

The headlight motor is round and black, about the size of a short medicine bottle and mounted on the back of the headlight.

rome99LS

Ok I found the headlight motor, but how can I tell somethin is wrong with it? I also checked the all the connections on the alt and battery and everythimg is tight. I dont get it car runs good but its just that battery light and headlight leveling on.

PureDrifter

iTrader: (10)

if both headlights move when you start the car (with the headlights on so you can see on a dark wall) then it's probably not the motors. If the motors are fine you'll need to start looking at the ride height level sensors.

rome99LS

Ok so check this out, I leave work togo pick up my son from daycare, n not even halfway home my car looses power completly..really in this 106° degree weather and my son in the backseat I was frustrated but kept calm. I got some jumps a few times, and made it to a body shop. So I borrowed some tools n took out my altenator n battery.....off top I assumed it was the alt. Once I got it to the parts store I had it tested and turns out I was right. Altenator was bad. Had the battery was ok, dead but ok.
Once again thanks for yall input...alt. Replaced and car is back to normal.

parkerjs

WOW. Two alternators in 6 months? Was the one you installed in Jan new OEM?

rome99LS

No it wasnt the Denso one like I wanted, it was like $400 the one I bought was $200 with a lifetime warranty. The Denso only had a 1yr warranty. If I didnt have the warranty, I would have been pissed if I had to pay another 200.

Yamae

If I were you, I would check the voltage first. As far as I check mine at the terminal of the battery, it never drops below 13.9V at the idle.

The other day, I have checked another car which had an after market generator of about one year old. The generator looked almost the same with the Denso's original but the regulator attached to the back side of it was different. The voltage was less than 13.3V and it turned on the battery light when the head light was on. Replacing the regulator to Denso's fixed the problem but it was very expensive. The regulator alone was about $150. This was more than the price of a rebuilt after market generator which had a non Denso's regulator.

Other than the generator issue, I would suspect contacts / terminals of 12V lines. The way I do is to measure the dropping voltage between the generator and the battery, and also between the battery and other terminals.

parkerjs

I think your experience will shy me away from the aftermarket alternator. I've never had a Lexus strand me ever and I'd sure like to keep it that way.

Thanks very much for sharing your experience.