I have projector lowbeams and seperate high beams and need help finding where to wire a diode to back feed lowbeames when highs are on. I want lows on with highs, i am not worried about heat since they are in seperate lenses. I do want to wire the diode between the switch and relays so as not to put extra draw on the wiring from relay to lamps. Any help with wiring diagrams and location where to tap the proper wires. I assume the best location will be either at the main switch or at the dimmer switch. Any help or ideas will be greatly appreciated.

 

I think you best location is the switch wire going into your lo and hi-beam relays.
Remember that the diode is directional.

 

I thought all the 09-10 were controlled by the computer and not relays. Am I wrong on this?

 

I believe you are correct. No relays on these trucks just a smart junction box. In my opinion the best way to accomplish all this would be to add a seperate power source direct from the battery using a diode from the high beams to power a relay, which would allow the lows to draw power straight from the battery while the highs are on. With the highs off the lows will draw power just like stock.

 

I would buy a 4 beam relay kit from Summit Racing. Then find or tap the wires near and headlamp socket with a tester. It would take a huge diode to carry the amps a headlight draws and you would still have the heat and voltage drop of the diode which would dim the low beam.
Painless Wiring 30802
http://www.summitracing.com/parts/PRF-30802/?rtype=10

 

Thanks for the suggestions and have used relays before and understand how to wire them. Just thought that if I could get hold of a wiring diagram i could just put in a switch or possibly a diode to stop them from turing off in the first place when the highbeam lever is flipped. There must be a circuit in the highbeam switch I could bypass.

 

The PCM usually drops the ground to the low beam and fog relays. You can diode or relay the high beam ground back to them possibly...

 

umm diodes don't limit current or voltage in a circuit they are one way switches. they allow flow in one direction and not the other.

 

Read your text books again they are not switches they are solid state devices in the category of semiconductors. Diodes have a .3 to .7 volt drop across them. They also do not handle high current without getting large or multiple diodes.

http://www.kpsec.freeuk.com/components/diode.htm

 

ok switch was the wrong word it was early, but you still would not use a diode to to limit current flow, you would a resistor(s) diodes are use to stop feed backs in circuits, not create them as i said the first time.

.3 to .7 voltage drops are nothing it is minuscule so you might use a diodes in conjunction with resistor(s) and maybe relay(s) to get the a proper circuit.

 

I meant they do not handle high current like a relay does. Not that they limit current they just get hot and melt under heavy loads.
A bulb is noticeably dimmer when you drop the voltage believe it or not. It is similar to the difference of headlights on a battery only and with the vehicle running.

 

After all of the talk above about the proper use of electronics terms.....

For best results, install relays in the wires that feed the lo-beam and hi-beam headlight bulbs. You can feed both Lo-beam ballasts with a simple 30amp relay but I use a 40 amp relay because the price difference is mote. You can feed both of the Hi-beam bulbs with the other relay. Use the switched power that originally fed the headlights to trip the relays and pull 40 amp fused power directly from the battery. Please use at least 12 AWG wire from the relays to both headlights and from the battery. You place the Zener diode (facing the proper way ) on the switched power feed close to the relays from the Hi-beam to the Lo-beam. This will keep the Lo-beams on when the Hi-beams come on and you will not encounter the low light output as the ballasts warm up each time that the ballasts are first ignited and come up to full operating power.

If you have DRL's, this "may" turn on the HID Lo-beams when you turn on the truck and run them all of the time that the truck ignition switch is turned on. You can temporarily turn off the headlights when not moving by pressing down on the park brake. Please do not use this override while driving!! Duh...

I have run this way on our Jetta for over two years with out any problems and you have the added benefit of having the other drivers notice you for a safer drive.

 

bringing this thread back up. I have my lights wired up according to my diagram, and I'm using the positive lines from the low beam to turn on my low beam hids. It seams as though the pcm is dropping the + to the lowbeams. Since the H13 has three wires and the ground is shared it wouldn't drop the ground or you would lose all lights.

So how can get the low to always stay on without flashing when you use the FTP?

I have dual bulb headlights and everything is wired and working perfect, except when I turn on the hid lows and then highs, the highs are dropping the lows. heres my other post that explains it better....

https://www.f150online.com/forums/me...or-diagram.jpg