headlights keep going out
 

I've seen endless posts regarding both headlights going out on the IS250 but no solutions, as this is quite common I feel there must be a standard solution, does anyone know of it.
regards godders

If you've got a rebuilt alternator, they often leave off a capacitor that filters out AC noise. I had the same problem right after I got a rebuilt alternator. I was going through headlight bulbs once a week. Its possible that the capacitor went bad on your stock alternator too. I guess the best way to check this would be with an oscilloscope. I realize thats not a common tool but they have 10 mhz USB ones now that you can get for like $90.

Unfortunately this is not the case I am still on the original alternator. Driving home tonight the offside headlight went out, I turn the lights off and back on and it's ok the rest of the journey, on Friday the same thing but both headlights went out. Very frustrating and dangerous.

Thats interesting. If I didn't know better, I would say that the relay is failing to stay latched. If its a normally open relay, which it probably is, then the coil inside the relay would need to remain energized to hold the relay closed. The reason I'm guessing its not the relay however is because both headlights should be on the same relay. Is this HID headlights or halogen?

They must be HID its an SE-L

Its probably just your HID ballast in that case. As you know, they send a high voltage ignition to get the bulb started, its like 20k volts. Then they drop down and run at a medium voltage like 80 volts or so as the bulb warms up. They should be running around 40 volts within a few seconds of warming up. If there isn't enough current or voltage to keep the reaction going inside the bulb, then it makes sense that it would just cut out.

If I were you, I'd just get aftermarket HID ballasts. I've had 3 pairs of the DDMTuning.com kits and they were excellent. Then I paid like 3x more for a fancy Moromito kit and it wasn't any better. It just had a really nice wiring harness that came with it.

If you want to diagnose this, I guess I'd try measuring VAC with a digital multimeter. Thats going to be kind of difficult because they intentionally shield the HID bulb connectors heavily due to the higher voltage. I don't know if these are like the Bosch units, but the Bosch units have a high voltage safety cap on the bulb socket where you plug in the bulb. It has a safety built into it. You could try a clamp meter in that case but I don't know if it would be sensitive enough to pick up such a small load.

Really appreciate the help, many thanks.

I'm having the same issue on my 07 LS460. Usually the passenger side, but sometimes the drivers side. Bought new OEM bulbs and that did not help. Debating if I should get new OEM ballasts or just a new HID kit all together.

Just FYI, the aftermarket ballasts are nowhere near the quality of OE. They won't ignite and warm up as quickly and they aren't as bright watt for watt. If you get the 55w, it will be brighter because your stock ballasts are 35w but if you get the 35w ballasts from DDMTuning.com or Morimoto etc, they won't be as bright as your stock headlights. You can also experience flicker.

I found the newer style D4S bulbs do not last like the old D2S bulbs (10yrs150,00mi) vs 4 years, 50,000 mi and one would drop off until cool. Come up orange but always strike cold and run like 10"... replaced the bulbs and problem solved.

That said I am sitting on 2 new OEM Toyota ballasts. Its coming up on 5mo now and no problems.

Anyone with flicker or drop out issues, swap bulbs from side to side. If the problem follows your bulb, replace them. Do not touch the glass. It will kill the bulb.

Im not saying they are they best or they will last but Morimoto XB 5500K D4S are $30 each. So far so good.