In my experience with a dual element failure, I have always found a tiny point of rock chip damage. This is sometimes hard to see, but is large enough for the required internal vacuum to become corrupted. Without a good vacuum the filaments fail instantly when energized. Don #1325 ----- Original Message ----- From: "Bob Brandys" <oehcs@xxxx> To: <dmcnews@xxxxxxxxxxx> Sent: Friday, September 29, 2000 10:08 AM Subject: Re: [DML] More from the strange headlight problem > I have been working on cars a long time. Over the years I have seen both front > headlight fail the the same time many times. I 'm not sure what causes this. > However, I think a voltage spike occurs when one light fails. The collapsing > -15 - 20 amps fieled could flow back to the other lights since they are on the > same circuit. > > This failure also occurred on older cars with independent voltage regulators. > However, I have never since this on a generator car. > > Bob Brandys > > > > Before posting messages or replies, see the posting policy rules at: > www.dmcnews.com/Admin/rules.html > > To address comments privately to the moderating team, please address: > moderator@xxxx > >