HID Headlight DRL Problem

[paulmackie]

Hi,
I am looking for a way to stop 9 volts but allow 12 volts in the same L33 circuit wire?

I have a Jeep Patriot 2011, 9 volts comes from a circuit board and goes straight to the high beam, which is a reduced dimmed light for the DRLs (Daytime Running Lights), when the high beam is activated it puts 12 volts in the same L33 circuit shown in the diagram; the low beam is activated by a separate circuit board.

The HID harness is plugged into the connector going to the headlights and has a solenoid in the HID projector that operates the high beam with the reduced 9 volts; when the car is put in drive the high beams (DRLs) come on, which even during the daytime are blinding for other drivers.

What I am looking for is some way to restrict the 9 volts going directly to the high beam wire (L33 white/pink, which operates the HID harness solenoid turning on the high beams) and effectively turn off the DRLs, but allow 12 volts if I need to use high beams.

If I could stop the 9 volts and allow 12 volts I would then add a relay using the 9 volts and turn on my fogs, which would replace the DRLs.

Thanks.

 

[ClydeCrashKop]

You could run the high beam pink wire thru a normally open relay that is activated by the low beam blue wire circuit. The high beam would only come on if you have the headlight switch on.

 

[audioguru]

Jeep designers are CRAZY to use high beams as a daytime running lights because they blind on-coming drivers when it is cloudy and at other low light times.
Smack! OOps, I didn't see the old lady walking across the road because I was blinded by that on-coming Jeep. High beams are used only when you have no on-coming traffic.
ALL Chrysler cars and lorrys DOO DAT. I hope Fiat fixes them.
Most cars dim the low beams or use the turn signal or fog lights for DRL.

 

[Diver300]

It would be a good idea to get an oscilloscope on line L33. I think that you will find that the brightness is controlled by PWM, not by a change peak voltage.

I guess that the 9 V is what you measured with a voltmeter. That would imply that the power is on for 75% of the time. However I suspect that the power is on for a lot less than that, because 75% would appear nearly as bright at 100%. I think that during the parts of the cycle where the power is off, the voltage doesn't fall all the way to 0 V, so the average voltage is much higher than the peak voltage multiplied by the duty cycle.

Vehicle circuits have to work with a range of supply voltages, and the change from 9 to 12 V would be badly affected by the battery voltage changing.