bcoulter

This may be a stupid question, but is there a difference between a headlamp ECU and a ballast for HIDs? I've been having the issues that some other members have had with my HIDs on my 2008 IS350 going off and on, and when I took it to my local Lexus dealer they said it was due to moisture getting inside the headlights and causing corrosion in the ECU and bulb connectors. When they're saying ECU, is that another term for ballast? They were telling me the solution was 2 completely new headlight assemblies, which seems a little extreme to me. If the issue is with corrosion in the ECU and bulb connectors, then replacing these parts would seemingly solve the issue, but before I do that, I just want to make sure that I'm buying the right parts. So if anyone can either confirm that the ECU and ballast are the same thing or explain the difference if they are 2 separate parts that'd be much appreciated. Also, yes, I know there are multiple different ECUs that do different things in a car, but I'm talking about controlling the headlight specifically.

Thanks!

Jeff Lange

iTrader: (1)

What is commonly referred to as the ballast is a part of what Lexus refers to as the ECU, on the IS these terms are interchangeable.

Jeff

ChumpusRex

I can't help on whether the term ECU could mean ballast in this context. These two words have completely different meanings, but it is conceivable that someone has got their terminology mixed up.

However, a burned-out/corroded ballast is not that uncommon a problem on the 2IS series.

It would be worth checking, however, that it is not the bulbs that are at fault. When a HID lamp is old, it will run for a few minutes, possibly flicker, then go out. (A defective ballast could also cause identical symptoms). Depending on the ballast, it might re-start - but some ballasts will automatically shut down if they detect a malfunctioning bulb.

The same thing happened with my IS250; changed the bulbs and it was fine.

Changing the ballast is a difficult job, which involves breaking open the headlamp unit (by heating it until the glue seal melts), and disassembling it almost completely to get to the wiring. You then need to reassemble the headlight unit and make a new seal where you broke the old one. Lexus won't do it. They'll insist on replacing the entire headlight unit.