Quad headlight conversion?????

[Red 'rado]

About 3 months ago I wired up the four pin relay to turn on both hi and low beams at the same time on my 2003. On the 2003 you can get them to work by pin 87 low beam, pin 85 high beam, pin 86 ground for high beam, and pin 30 to 12 volt source. Everything worked fine until today.

 

I washed my truck in the garage cause it is 25 degrees outside. About halfway through the wash I noticed the low beam lights were on, even though the truck was not running and I know for a fact the lights were out when I was washing the front end. I thought this really strange so I got inside and tried to turn them off. I couldn't. So I started the truck then turned it off and the lights stayed on.

 

My mind started wondering the worst, I just put in a new PCM custom tune yesterday and was trying to think how that could possibly have an affect on the headlights.

 

I finally decided to remove the 12 volt power that fed the relay for the quad headlight setup. Voila, the low beams went out. I started the truck, they came on, I turned off the ignition then 10 seconds later the lights went out as they are supposed to.

 

Can anybody explain that??? Was the relay shorting out from the water, or is the relay just shot??

 

I don't know what to do now.

[SilveradoWV]

I actually just had to replace my relay, but mine wouldnt work at all, it was like I didnt have the 4 headlight conversion. My relay just went bad I guess because I could beat on it with a hammer or whatever I had with me and then it would work! I have always sealed my relay connections in silicone or a mile of electrical tape to keep water out!

[lrymal]

I sure can't explain that, but a far simplier way of getting all four lights on when you go to high beam is to add a diode to pin 85 on the high beam relay and pin 85 on the low beam relay. About a 15 minute job. Most time consuming part was carefully unplugging the two relays to install the diode. Been working perfectly nearly for a year:

 

[Kevin zellweger]

hey Irymal, What kind of diode did you use? I would like to try that with mine.

Thanks

[03GMCinBC]

I would like to do this mod too! I dont know much about electrical but the electrical outlay looks pretty strait forward. One question

 

Where do i get the Diode and when I go to the shop, what exactly do I look/ask for?

 

Thanks

[lrymal]

Just a very cheap diode. Radio Shack. 1/8th watt to 1/4th watt would be fine. Don't attempt this if you aren't comfortable with basic electronic skills, including soldering.

 

The relays' triggering voltage is from the switch and is very low on amperage requirements, hence the low power rating of the diodes.

 

Now, if you have never done anything this, then DON'T learn how with this proejct. Get someone who is comfortable with simple electronics. Don't just wrap the diode's leads around the relay pins. You have GOT to solder. And apply solder toward the pin's attachment to the relay. You don't want solder toward the relay pin's end because the solder will thicken the pin, making it difficult to reinsert the relays into their socket.

 

This is really a very simple project, but you gotta know soldering techniques. And you need to be familiar with the appearance of a diode. Notice it has a bar at one end. Notice how that is drawn on my diagram.

 

Basically, that is it, at least for a 2003 Z71.

[durado]

This is the best way to do this. Just use 12 volt diodes. To take the quad beam system one step further - add another diode and jumper from the low beam diode to the same cooresponding relay pin on the DLR relay. This will give you a 6 beam hi and will allow you to turn on your factory fogs with just your DLRs.

[lrymal]

I keep getting private mail on this. Y'all, go public!!! Others can learn. Most of the mail is asking how and why this works.

 

If, for an experiment, you hook up the pins 85 on the two relays, you are providing "turn on" voltage to the two relays, and any other relays you want to turn on.

 

But, these relays (high beam AND low beam) will ALWAYS kick on as soon as your lights are commanded to turn on. BAD IDEA. Nobody will like you anymore. Hence the need for the diode.

 

What the diode does is pass voltage in only a single direction. So, when you flick your brights on, voltage is passed from the high-beam relays, through the diode, to the low-beam relay, just as if you were using a straight wire with no diode.

 

When you flick your lights to low beams, the diode BLOCKS the voltage traveling back to the high beam relay. That is why this works.

 

This is also why the low-beam does NOT dim when you flick the high beams on with the diode installed as what happens with older, yet similar, modifications. When the relay kicks in, it is connecting a high current path for the lights. That part of the supply current is not affected by the modification. It is not even touched by the modification. A relay is used to keep the high current away from any controlling switch.

 

Electro-geeks can ignore the following, and probably this whole message:

 

A simple relay is energized by a voltage source that comes on via a switch. The relays connects the "business-end" voltage. This keeps all the hard stuff off the switch. Which is another reason why I think the "smoking switch" problem doesn't exist on the newer trucks.

 

I probably made all of this as clear as hooking up baling wire to a Ford.

[esu78]

nice i will have to try this mod on my 03 tahoe.

now is there a 'hotwire' hookup for the Fog Lamps?

so now when i flick to Hi-Beams the Fog Lamps will remain on?

 

seems like another diode would have to be run.

 

please let me know.

thanks!

 

John

[muddog]

I would love to do this....do you know if this will work on my '96 1500??

 

Thanks

[stebob]

Good question, Mud! I have a '97 and wondering the same.

 

[muddog]

anyone have a clue?? thanks

[99GMCZ71]

I would love to do this....do you know if this will work on my '96 1500??

 

Thanks

From doing some research on all the trucks boards, the pre 98 trucks must use a relay setup. The 99 to 02 you can ground some yellow wire under the relay center and all 4 will come on. 03 and up, the diode will work. If I'm wrong someone correct me, but this is the best info I could come up with.

[builderpaul]

Don't just wrap the diode's leads around the relay pins. You have GOT to solder.

This is an easy mod. I have it on my 2004 HD. I just shoved the diode ends into the sockets and reinstalled the relays. It has worked fine for 4 months now. I don't know where I would solder but so far I haven't needed to.

[the blur]

is the diode backwards in that picture ??