Charger1970's world famous headlight relay upgrade

[myk]

The new relays go in and a 30 amp fused wire added from the alternator

So....All you do is cut the harness just before the 'rad support, install a relay for both low's and high's, splice both ends of the harness into the relays, then run two fused wires from the alternator into the relays?  What part of the alternator is being wired to the relays?  Also, I take it that you need a separate switch to choose between low's and high's?  Why can't the dimmer switch do that?

This is good stuff...

[73Charger]

that was an intersting article about how the light diminishes with voltage. And i always thought my lights were pretty bright. 
although, i've had the problem of losing my lights on another car once, and was glad to have a backup - aftermarket foglights were installed and i used them to get home. 

[Blakcharger440]

Excuse my dumb question but what exactly does this headlight relay upgrade do??? 
Sounds like something I should know about and do for my mopars.

[phat69charger]

Excuse my dumb question but what exactly does this headlight relay upgrade do??? 
Sounds like something I should know about and do for my mopars.

In a nut shell the current that goes to your headlights goes through the bulk head connector and headlight switch then to the headlights in the factory harness which is resistance and lowers the voltage going to the headlights and wears the headlight switch out prematurely, the relay upgrade bypasses the dash switch and the current goes through the relays which allows more current to the headlights.

The headlight switch is just a off on switch for the relays after the upgrade

[Blakcharger440]

Sounds good to me. Thanks!

[toast007]

Okay, my turn for questions.

1. A little fuzzy here.  This controls the headlights only.  So, does this mean that turning on the headlight switch on the dash will not also turn on the tail lights and side markers?

2. Will the floor mounted dimmer switch still work or do you install a different toggle switch for the high beam low beam?

[Ghoste]

Those parts function as normal.  What it means is that the higher amperage required to operate the filaments themselves inside the lights, does not flow through the main wiring harness and the headlight switch.  The headlight switch will use the power that is already flowing through it to operate the relays and the relays will bring the higher amperage straight off of the alternator.  This avoids the dimming at idle and a few other problems that Mopars are known for with their headlights.  It's especially useful if you put higher ouput lighting in such as halogen bulbs.
The switch and extra wiring act as a resistance for the power to flow through instead of being used to power the lighting filaments.

[toast007]

Oh!!! I see now!   That was a terrific description of it, I really appreciate it.  Looks like I will be doing the upgrade too!  First I have to figure out why only the right side marker lights work on my car.  You see, i bought this one in pieces not running so I have all kinds of gremlins to find and this sure sounds like a great way to get rid of that headlight realy to me!

[1970Charger500]

I know this is an old post.. but i just finish (almost) this upgrade.. one stupid question I have is which post on the alternator is the positive?  I'm doing some other stuff too so the car isn't running or I'd put a multimeter on it.  My guess is the one with the largest gauge wire?  (the one of the 3 that screws on)

This is on a '70.. Thanks!

[Plumcrazy]

I know this is an old post.. but i just finish (almost) this upgrade.. one stupid question I have is which post on the alternator is the positive?  I'm doing some other stuff too so the car isn't running or I'd put a multimeter on it.  My guess is the one with the largest gauge wire?  (the one of the 3 that screws on)

This is on a '70.. Thanks!

You guessed right.   

[Nacho-RT74]

I made a complete A/C blower and headlights relay upgrade but I installed everything underdash to save from water, heat, grease, rust and dust. The red line is all along under dash. Is Feeded by the black side of ammeter studs what is the one that comes from Alt. I hidded the headlights relays on kick panel area. rest of relays are hidden underdash

Another interesting stuff is I re-routed all the terminals, no cut any wire. Just removed the right plug terminal and inserted on relay plug. Then used a new wire same color with new terminals between relay and original location of the one removed before to reset the original route and that's all.

In that way I have everything protected and hidden. No visible relays.

To give you a guide of colors:

Big red wire all along is the one that feeds all the relays with a fuse link ( blue )

red and violet wires are the low and high beams. Green on that side is the signal coming from headlights switch.
brown and dark green on center are high speed ( byapssing speeds resistor ) and heater speed blower. Plug is the A/C control switch
at the right side of diagram, tan and light green are low and med blower speed. These wires comes from lever A/C switch. Green is the one that runs directly to blower that feeds blower once speed is setted on lever switch.

This diagram is from 3rd gen, but works to any model.

As stated, this way to go makes NO CUT ANY WIRE. Just remove terminals from plug and insert on relay plug. Then add a same color wire to restore the wire removed from original plug already with relay upgrade. With this way you get also the right reading on ammeter as far you use the black side of ammeter.

To get it good and safe you need a charging wiring upgrade. DON'T DO IT with ONLY stock charging wiring through bulkhead. You need to get the parallel charging wires throught firewall to work together with stock wires

I can give more details if you need. just ask.

A/C Plugs are just a guide even the right shape. I can't recall right now the right wires cavities location, but you got the idea.

Sorry If I made now a big diagram, more than I usually posted, but now I have a 17" monitor 1280x1024 pixel definition

[NHCharger]

My turn for a dumb question. I remember this thread from the old board. I was going to do this conversion back then but I thought it was mentioned that you had to modify and drill through the bulkhead connector. Obviously after looking through this thread that is not the case. What mod was I thinking about? Or is it just CRS kicking in.
From the diagrams it looks like all 14 gauge wiring. How about the wires running from the alt. to the in line fuses, 14 gauge also?

[COKE]

Another interesting stuff is I re-routed all the terminals, no cut any wire.


Yes,i,m agree with this.
I did my relay headlight conversion last summer.
I built a connector to get the current fron the headlights harness ,cuting a H4 lamp welding wires on the interior therminals an refilling it with a hot glue gun,to isulate them.
Here is a pic:



What a  difference since i installed the relays.
What a difference..

[NHCharger]

Just finished doing the upgrade. What a difference. I also upgraded to Halogen headlights since I have no clue how long these current bulbs have been in the car.
This was so easy a caveman could do it.
I liked what Ghoste had mentioned about hiding the relays under the battery tray.
In the first pic I have prewired the two relays making sure I left plenty of wire. I then sprayed some rubberized undercoating on the bottom of the relays to keep them waterproof. I taped off the rest of the relay to protect from overspray.
In the second pic I have the relays mounted under the battery tray. I cut the two headlight wires between the starter relay and battery and made the connections there. The two feeds from the alternator and the grounds run forward up between the battery tray and the inner fender.

[1970Charger500]

OK guys.. just now got finished with this conversion.  before the conversion my headlight motor didn't work (1970 = non-vacuum) probably because my headlight switch was bad.  I did this relay upgrade and had my switch refurb'd by performance car graphics ($28 bucks).  cranked it up, hit the headlights and was amazed when the headlight doors opened and the lights came on.  even my dash lights work now.

BUT.. My headlights won't turn off!  turn the switch off of and nothing happens, turn the car off & back on with the switch off.. nothing, lights are still open, headlight doors still open.  My guess is the relays are wired slightly wrong?

any ideas?

Thanks,
Paul

[Rolling_Thunder]

OK guys.. just now got finished with this conversion.  before the conversion my headlight motor didn't work (1970 = non-vacuum) probably because my headlight switch was bad.  I did this relay upgrade and had my switch refurb'd by performance car graphics ($28 bucks).  cranked it up, hit the headlights and was amazed when the headlight doors opened and the lights came on.  even my dash lights work now.

BUT.. My headlights won't turn off!  turn the switch off of and nothing happens, turn the car off & back on with the switch off.. nothing, lights are still open, headlight doors still open.  My guess is the relays are wired slightly wrong?

any ideas?

Thanks,
Paul

I bet it has something to do with the "concealed headlight relay" under the dash...    it powers both the motor for the headlight doors and the headlights themselves...     sounds like it is getting a constant 12V...      that 12V gets directed thought your headlight switch...     maybe it was improperly referbed ?

[1970Charger500]

ah.. I unplugged that 'headlight relay' under the dash when i was doing all of this.. I bet I just hooked it up wrong; I'll check that after work.
Thanks!

[JimShine]

We did the head;ight relay mod on the General Lee before doing the Bandit Run thing a few weeks ago. That mod is essential! I can't believe how big a difference it made. The car has real, steady, bright headlights now.

[1970Charger500]

well.. more info.
My neighbor helped me today on this and we eliminated a lot of stuff but didn't fix it.  When my high beams are on everything works perfect.  but with low beams on the headlight doors will open & come on, but when the switch is turned off, nothing happens.  the doors stay open and the lights stay on.  if you turn the car off and back on (with the headlight switch still off and the low beams on) the lights and doors turn on/open.

so i suppose it IS either in the dash relay or the dimmer switch?  I checked and I didn't unplug the dash relay when doing this so i'm pretty sure it's hooked up right.  the only thing I didn't try is switch the green and blue wires that go to that relay.

I suppose i'll try that tomorrow.  any other suggestions?
oh, and my lights don't really seem to be real steady; i can't really tell for sure until i drive it at night though, haven't done that yet.

Thanks again.

[Plumcrazy]

I bet it has something to do with the "concealed headlight relay" under the dash...    it powers both the motor for the headlight doors and the headlights themselves...     

The concealed headlight relay does not power the headlight bulbs.  The power that comes out of the headlight switch in the light green wire goes to the relay and turns it on, the relay then switches power from the wire to the headlight door motor that closes the doors to the wire to the headlight door motor  that opens the headlight doors.

The power then continues along the light green wire to the floor dimmer switch which directs that power to the low or high beams.

I would disconnect the light green wire from the concealed headlight door relay.  If the lights stay on the problem is possibly in the headlight switch.  If the problem is fixed then for some reason the relay is putting power into the light green wire which it should not be doing.

[2Gunz]

well.. more info.
My neighbor helped me today on this and we eliminated a lot of stuff but didn't fix it.  When my high beams are on everything works perfect.  but with low beams on the headlight doors will open & come on, but when the switch is turned off, nothing happens.  the doors stay open and the lights stay on.  if you turn the car off and back on (with the headlight switch still off and the low beams on) the lights and doors turn on/open.

so i suppose it IS either in the dash relay or the dimmer switch?  I checked and I didn't unplug the dash relay when doing this so i'm pretty sure it's hooked up right.  the only thing I didn't try is switch the green and blue wires that go to that relay.

I suppose i'll try that tomorrow.  any other suggestions?
oh, and my lights don't really seem to be real steady; i can't really tell for sure until i drive it at night though, haven't done that yet.

Thanks again.

um.............


Im not familiar with the 73 charger however....

Most relays have 5 inputs/outputs

2 of which power the coil

1 of which connects directly to the battery.

1 of which is the normally closed (no power to coil the connection is complete .... In our situation you should have nothing connected to it).

1 of which is normally open (No power to the coil and the connection incomplete)


I suspect you somehow have used all the terminals on the relay and this is causing your madness. You only need and want 4 connections to be made.


I dont understand how or why the headlight motors are even part of the equation. Once again Im not familiar with the 3rd gens...

But it seems like the motor control would be a separate circuit all to itself.

Assuming Im correct (3rd gen guys?)  I would pull the new relays and get the motors to work correctly first. Then add the relays back and make the headlights work after.


Oh.... and a wealth of info on relays and specifically the very popular Bosch automotive relay.

http://www.bcae1.com/relays.htm

[71_deputy]

read my post of the upgrade with the headlight motor!

http://www.dodgecharger.com/forum/index.php/topic,8077.0.html

John Mac

[mopar0166]

Cant believe i have been reading this orum or over a year and just found this.  Im guessing it is sae to say its good for 69 charger?   I had issues last night with my headlights turngin on and off.

Im guessing its ether the foot dimmer switch or a connection some where that is loose. 

If you have headlights on for long periodsof time im guessing this up grade will put less strain on the light switch as well. 

ill print out the parts list and first diagram to do this tonight!~    any suggestions with the headlight thing let me know

ocean city, md   2 days 15 hours 25 minutes 

[mopar0166]

What Guage wire is used for the upgrade to the harness 

12ga 14ga ?

can all those parts be found a the the local hardware store ?

[Rolling_Thunder]

I use 12ga wire to pull power from the source to the relays.