A switched voltage source when the headlights are on.

[Westcoaster]

Does anybody know of a place in a 987 where I can find a signal to turn on a relay when the headlight switch is in the 'on' position?

The second best signal would be one that is only present when the engine is running.

Thanks!

[pjslowik]

If you're just running a relay, tap into the power feed for one of the headlights. When the light is turned on, the relay will actuate. I wouldn't use that feed to run anything else though.

Oh, and be sure to add a fuse.

Edited February 2, 2007 by pjslowik

[Westcoaster]

If you're just running a relay, tap into the power feed for one of the headlights. When the light is turned on, the relay will actuate. I wouldn't use that feed to run anything else though.

Oh, and be sure to add a fuse.

That won't work on my car, the voltage is not constant at the headlight. See the attached photo... all the relay did was buzz!

Edited February 2, 2007 by Westcoaster

[pjslowik]

I can't quite make out the settings on the scope. But, if you have hid's, did you tap before or after the power module? You would have to tap the DC feed to the power module. Where did you probe with the scope? I'll have to look at a drawing, but if you're proficient with the scope you prob kbow what you're doing anyway.

[pjslowik]

I see what you are trying to do by your other post. HID runs on AC and the square wave is the clipped AC needed to boost the 14VDC to 20Kv. Seems to me that the input should be clean. Keep in mind that once HIDs start and fail, they need a cool-down time before they'll light.

Sorry, but I think the only correct and legal way to convert to HID is spending the grand for the factory retrofit kit. Good luck though.

[Westcoaster]

I see what you are trying to do by your other post. HID runs on AC and the square wave is the clipped AC needed to boost the 14VDC to 20Kv. Seems to me that the input should be clean. Keep in mind that once HIDs start and fail, they need a cool-down time before they'll light.

Sorry, but I think the only correct and legal way to convert to HID is spending the grand for the factory retrofit kit. Good luck though.

Actually my car came stock with regular halogens, although it is a Canadian spec car so it also has DRL activated. The signal shown on the scope was taken right at the headlight bulb connector where I would have expected a solid DC voltage. What I saw was a 14v DC signal with a dropout every 9 ms.

So that is why I am in search of a trigger for the relay, that way I could run the aftermarket HID kit powered through a relay directly connected to the battery. What I want is a clean source of 12v that is only 'on' when either the car is running or the headlights are in the 'on' position.

As for legality, yes I know the story around HID's, self-leveling and washers however; this car has projector style lamps that provide a precise cutoff effectively controlling the light throw from the lens (I suspect nearly identical to the factory HID), the only things missing would be the self leveling (a small issue) and the washers (my car is never dirty! :clapping: )

I appreciate any other ideas you might have, Thanks for reading this and the other posts for background)!