Both filaments lit when on high beam FYI
 

Possibly a new solution to an old problem.<br><br>I wanted to have my low beam lights to stay on when switching to high beams. I was poised with pen in hand getting ready to write a check for a Brite Box. Then I remembered that I was an electrical engineer and should be able to do this myself. I located the schematic for the lighting circuit in the manual and found out how it works. A simple procedure will eliminate the need for the Brite Box. There are those who will say that the light switch can't handle the current of both filaments being on at the same time. I have a 2002 so my switch maybe different than earlier years. I did, however, perform this modification to a friend's 2001 without any problems at all. To do the mod, remove the panel below the steering column. This will expose a bundle of wires coming from the multifunction switch as well as the horn, cruise control, etc. The wires of interest on my 2002 as well as my friend's 2001 are light green and violet with a white stripe. There are two light green wires. Make sure of the one you need before doing the mod. I used a piercing circuit tester light and found the correct light green wire by grounding the tester and piercing each light green wire and watching which wire caused the tester light to go on and off when the light switch was turned on and off. Having located the correct wires, I used a wire tap connector to short these two wires together. The wire tap is designed to allow you to connect a new wire to an existing circuit. In other words, one side of the tap goes all the way through and the other dead ends. Take a knife and cut the dead end plastic out so that both wires can go all the way through. Place both the light green wire and the violet with white stripe wire in the tap and press it home with pliers. Be careful not to short the pliers to ground while doing this. I used a dab of dielectric grease in the tap just to be safe from corrosion later on. What this mod does is simply short across the low beam disconnect contacts of the multifunction switch. This will make the low beam filaments light as long as the light switch is turned on with the multifinction switch in either high or low beam position. I can now see the road better and it cost me $0.11 instead of $95.00. Questions are welcome.

Re:Both filaments lit when on high beam FYI
 

Wouldn't this put on both lamps (high and low) regardless of the switch position? Seems like it would send power down both wires no matter which one is supplying it.

Re:Both filaments lit when on high beam FYI
 

It would do that, but you could accomplish this with a diode between the two.

Re:Both filaments lit when on high beam FYI
 

[quote author=DynamicalyUnstable link=board=7;threadid=13544;start=0#msg213769 date=1069726140]
Wouldn't this put on both lamps (high and low) regardless of the switch position? Seems like it would send power down both wires no matter which one is supplying it.
[/quote]
No. Check the wiring in the manual. These two wires are not part of the high beam circuit in any way. The high beams are not affected.

Re:Both filaments lit when on high beam FYI
 

[quote author=Haulin in Dixie link=board=7;threadid=13544;start=0#msg213777 date=1069726706]
It would do that, but you could accomplish this with a diode between the two.
[/quote]
Not true. It won't do that.

Re:Both filaments lit when on high beam FYI
 

[quote author=rattle_rattle link=board=7;threadid=13544;start=0#msg213821 date=1069731217]
[quote author=Haulin in Dixie link=board=7;threadid=13544;start=0#msg213777 date=1069726706]
It would do that, but you could accomplish this with a diode between the two.
[/quote]
Not true. It won't do that.
[/quote]

It would seem that when the high beam wire was energized the power would pass the diode and energize the low beam wire. When the low beam wire was energized the diode would block the power from reaching the high beam wire.

Re:Both filaments lit when on high beam FYI
 

[quote author=Haulin in Dixie link=board=7;threadid=13544;start=0#msg213849 date=1069733639]
[quote author=rattle_rattle link=board=7;threadid=13544;start=0#msg213821 date=1069731217]
[quote author=Haulin in Dixie link=board=7;threadid=13544;start=0#msg213777 date=1069726706]
It would do that, but you could accomplish this with a diode between the two.
[/quote]
Not true. It won't do that.
[/quote]

It would seem that when the high beam wire was energized the power would pass the diode and energize the low beam wire. When the low beam wire was energized the diode would block the power from reaching the high beam wire.
[/quote]
I guess I'm not following you at all. The modification that I outlined does not have anything to do with the high beam circuit. What this does is cause the low beam filament to stay on all the time and not be switched off. Effectively, the connection I am adding is shorting across the low beam switch contacts in the multifunction switch. When you pull on the multifunction switch lever with the stock setup, two things happen. When going from high beam to low beam, the high beam circuit is disconnected from ground and the low beam circuit is connected to ground. When going from low beam to high beam, the opposite happens. With the modification I described, the low beam stays grounded all the time and therefore stays on all the time (assuming that the headlight switch is on). Again, the high beam and low beam circuits are completely separate and this modification is only connecting wires together in the low beam circuit. No isolation diode is needed because there is nothing to isolate. Trust me, this works. I has worked on three different trucks that I have done it to.

Re:Both filaments lit when on high beam FYI
 

At least I'm not alone, DA got the same thing I did ;)

Re:Both filaments lit when on high beam FYI
 

[quote author=Haulin in Dixie link=board=7;threadid=13544;start=0#msg213926 date=1069745969]
At least I'm not alone, DA got the same thing I did ;)
[/quote]
I wasn't trying to prove you wrong or anything, just trying to explain what was really happening in the circuits. One could use an isolation diode on the high beam circuit and feed it over to the low beam circuit. You would have to use a diode and a relay that way. I can see how this may have been intrepreted that way. ;D

Re:Both filaments lit when on high beam FYI
 

Looking at the wiring diagram for my truck on Alldata and indeed the wires are lt green and violet/white and all on the low beam circuit. The &quot;other&quot; light green wire RR was talking about is for the flash feature while on brights.

I am going to try this, Thanks for the info RR.

Re:Both filaments lit when on high beam FYI
 

me too.

rr, how long have you been running this way? Im just scared of messing up my lights. I had my light switch burn up, and lost my lights one time at night, in the rain going 70mph. scared the dickens outa me.

Re:Both filaments lit when on high beam FYI
 

[quote author=Palmetto_kid link=board=7;threadid=13544;start=0#msg214136 date=1069797115]
me too.

rr, how long have you been running this way? Im just scared of messing up my lights. I had my light switch burn up, and lost my lights one time at night, in the rain going 70mph. scared the dickens outa me.
[/quote]
I've been running this way a little over a year. The other two trucks I did it to have been on the road that way for about 8 months.

I have had no problems with this mod but one never knows. What this mod does is bybass the multifunction switch contacts that control the low beam. The high beam and the low beam use separate ground connections and separate power connections. The ultimate solution is to add relays to the headlights at a location near the headlights. I used Radio Shack automotive relays good for 30 amps, two at each headlight. There is another thread describing this mod too. If I find it, I'll post the link.

That's pretty slick
 

Just leave the low beams lit all the time and add hi-beams when you direct it.
At first I was confused as others were, and had no schematic to reference. Now that it's explained, no need for a schematic. You're just leaving the low beams on all the time.

Now, will my '95 do the same thing? I'm sure the switch is different, but might the same features be there? Again, I'm flyin' blind- no schematic to guide me.... :'(

Re:That's pretty slick
 

[quote author=HammerMTB link=board=7;threadid=13544;start=0#msg214173 date=1069802044]
Just leave the low beams lit all the time and add hi-beams when you direct it.
At first I was confused as others were, and had no schematic to reference. Now that it's explained, no need for a schematic. You're just leaving the low beams on all the time.

Now, will my '95 do the same thing? I'm sure the switch is different, but might the same features be there? Again, I'm flyin' blind- no schematic to guide me.... :'(
[/quote]
I have no access to '95 wiring. The trucks I did were '01's and '02's.

Re:Both filaments lit when on high beam FYI
 

i did this to my 96. wire colors are the same