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She Don't Smoke!
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Discussion Starter #1 (Edited)
All on Headlight Mod Guide
This is just a guideline on how to do this, there are many ways you can do this

Things you will Need:
  • Wire
  • One 30 Amp Relay
  • One 20 Amp Fuse and Fuse holder
  • Two Splice Connectors and two Spade Connectors
  • Two eye connectors
  • A couple screws (to mount devices)
Wiring Diagrams:

This is the diagram of the composite headlight system w/o driving lights.


Here is a small diagram for the headlight mod.


Lets Get Started!

1. Determine where you are going to place your fuse holder, relay, and where you are going to splice into. Cut each wire long enough. You will need to run to battery positive (with fuse), a ground of some sort (behind relay or fuse mount), and to the two spliced connections in harness.


2. Run your power wire from battery to your relay, not forgetting to install a 20 amp fuse.

3. Splice into the harness with your splice connectors. The wire colors should be Tan and Light Green. Connect your wires and run them to your relay. Installing them in the proper place on the relay (see diagram).


4. Connect all wires properly to your Relay and run the ground behind the mount for relay or fuse. Mount Relay and Fuse holder securely.

5. At this time test to make sure everything is working properly. Low beams, then when High beams are clicked on you should have both High and Low beams turned on. If it does not work properly check your fuse and make sure all your connections and ground are good. Also, make sure that you properly placed wires on the right places on the relay.

Here is how my setup looks before I taped it all up.


You may add a switch in this setup but I didn't add that in this guide as I didn't install it because I didn't want it lol.

This guide isn't completely finished, I want to get pictures of the connectors themselves for you guys and will clean up the guide a little bit sometime during the week...
 

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Great post! I was looking at doing this mod myself & this post will really help me out. Thanks
 

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Theres a far easyer way of doing this.

I got an old style foot dimmer switch on the floor,one wire to a Key on only power supply from the underdash convieniance center to the switch,one wire from the switch spliced into the high beam green wire in the dr side fender harnass.
This setup will also turn on the blue high beam on light in the dash.
It works fully independant from the high/low lever wich stays fully operational as well.

I installed this set up in all my GM trucks and cars for yrs allready.
 

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She Don't Smoke!
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Discussion Starter #4 (Edited)
Bison I wouldn't consider that far easier. Just a different way of doing it. Still about the same level of difficulty, just your way eliminates the relay it looks like.

Like it says on the top of the guide, "This is just a guideline on how to do this, there are many ways you can do this"
 

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Mike and I had a discussion on this before about doing this with a simply Diode as well...there's many ways to do it, and each person will find a way that each is hard and each is easy...it depends on your experience and knowledge level. as well as willingness to mess with stock wiring.
 

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Hey Mike I'm having a problem doing this to my truck... I can't find the wires you pointed out and ironically all my lights are on anyway...

oh wait:D:D:D:D this doesn't concern me:D:D:D:D












on a more serious note -awesome writeup. A+
 

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headlights

Diode is a cleaner way of doing this.Can be concleded in factory harness.Minimal wiring needed.
A diode is a 1 way valve for electricty.
1 side can be hooked up to positive on high beam and other side on positive on low beam,When high beams are on 12 volts flow over to low beam positive. When low beams are on the 12 volts cant flow over to the high beam side because of the 1 way valve effect of the diode.No relays to wire up or make heat and burn out.
Radio shack sells for under $5.00.
I will try on wifes taho this weekend.
 

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Diode is a cleaner way of doing this.Can be concleded in factory harness.Minimal wiring needed.
A diode is a 1 way valve for electricty.
1 side can be hooked up to positive on high beam and other side on positive on low beam,When high beams are on 12 volts flow over to low beam positive. When low beams are on the 12 volts cant flow over to the high beam side because of the 1 way valve effect of the diode.No relays to wire up or make heat and burn out.
Radio shack sells for under $5.00.
I will try on wifes taho this weekend.
once again:
All on Headlight Mod Guide
This is just a guideline on how to do this, there are many ways you can do this
Have a nice day
 

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Theres a far easyer way of doing this.

I got an old style foot dimmer switch on the floor,one wire to a Key on only power supply from the underdash convieniance center to the switch,one wire from the switch spliced into the high beam green wire in the dr side fender harnass.
This setup will also turn on the blue high beam on light in the dash.
It works fully independant from the high/low lever wich stays fully operational as well.

I installed this set up in all my GM trucks and cars for yrs allready.
You're not taking into account the amp draw of the lights from whatever 'key on only power' you're taking it from. Easy way to blow a fuse here, just turn on your high beams with, say, your fan blower on high and POW, blown fuse.

Pulling the power from the always-hot headlight fuse would be better as I believe they're rated enough for both lights (some cars/trucks you can even find a sweet spot with your dimmer switch where both are on without a mod, but you gotta hold it there). This would also allow you to keep the all-on while the engine is off, which I suppose could be useful sometimes? Dunno.
 
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never blew a single fuse yet after 15 yrs of use on my 89. this truck dont have daytime running lights so my high beam substitutes for that. So these lights are on all the time i 'm on the road,I burnt out a couple bulbs over the yrs though.
 

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??>>>>>>>>>>>>>>>...............////

..........Can be concleded .....................
what exactly are you referring to "concleded"??
 

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im nearly positive he meant concealed
 

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Reverse the polarity once a year and the bulbs will last longer.
 

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Reverse the polarity once a year and the bulbs will last longer.
Really? I've never heard this one before. For incandescent bulbs, it's just a resistor the current flows through. Reversing the polarity just reverses the direction of the current flow. I'm curious as to how this will extend a bulb's life span.

I know that voltage surges/spikes will help shorten the bulb's life, so making sure the generator/alternator's output is capped at the desired maximum voltage, or better yet, adding some circuitry to keep the voltage constant will help. Hmmm, got me thinking now...
 
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great write up mike, might just do this on the burb
 

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I plan to do this right away and the diod way seems like the bomb. Knowing very little about electrical, What exactly am i buying (part #, propper name etc)Can i solder the wires to this diod without fear of damaging it? Anyone got pics of the diod method?
 

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She Don't Smoke!
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Discussion Starter #17 (Edited)
The diode way isn't the best way to do this on our trucks since we do not have relays to control the headlights. If we had relays in the fuse panel (underhood) then that would be great, but we don't. Not sure about you, but I don't know if I would want to run two 4 headlights out of one tiny little wire (setting up diode to cross the hi and low beam wires). Scary enough just running two each out of those skinny wires lol.
 

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I did the 4 high mod on my '97 with the relay. Worked great. At least until something happened to the relay and left my lights on all night. :( The only thing I suggest is to run the main power for the relay to a key on source. You can find spare spots in the fuse panel. This would have eliminated the problem I had.

Good write up!

Bill
 

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A word of caution on the use of scotch-lok "T" taps. I work on the largest fleet of city owned vehicles in Los Angeles. Our radio shop used the "T" taps for all of their needs. After about 4 months of use we had computer failures, funky codes and all sorts of issues, even a fire. The culprit was the "T" tap eventually working loose and arcing against the wires, eventaully tripping codes and backfeeding current. All of this wasnt good for the ECM's.
Long story short, we had to recall ALL of the vehicles done with "T" taps and soldier/shrink wrap the connections. A lot of work but 100% guaranteed not to fail. As with all computer controlled vehicles it is best to disconnect the negative cable (both of them if equipped) before working on the electrical system.
 
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