tshort

I would like to add 2 relays to my headlight system. One for highs and one for lows. I'd also like to do it as simply and cheaply as possible. Can I just bring the wires over from the horn relay? If so, does anybody have a diagram that shows what wires are what? Also, what do I need to get? I assume 2 30 amp Bosch relays and maybe a few connectors. Anybody done this?
I know many have added relays, but has anyone done it using the existing wires?
Thanks.

crazywelder

Give MAD a call, they have a kit with everthing you need, or you can just talk to him on the phone, very freindly and informative. Has lot's of electrical improvement kits.

http://www.madelectrical.com

tshort

Yeah, but they charge $24 a piece for each relay and wiring. I believe you can get the relay at a local store for around $5. What's the other $19 ($38 for 2) for? Advice and instructions??

rcread

Have you seen what consultants charge these days? $38 is a bargain.

SIXFOOTER

I start at $75 and go from there. The MAD deal is a good one, but if you want to do it cheap, get the relays locally for whatever they cost, some wireing and your good to go. The MAD schematics ans instructions are free.

tshort

Great, then what I'm looking for are some specifics on what wires do what at the horn relay.
Anybody have a wire diagram for the horn relay on a '69?

S489

no help on the 69 wiring diagram; i have a 74 and have found errors in it. here is a link to relays, wiring and typical application diagrams (several clicks away):
http://www.partsexpress.com/webpage....TOKEN=59300176

SIXFOOTER

Read This
http://www.madelectrical.com/electri...adlights.shtml
at the bottom of page 1 is a pic.

S489

it may not matter much what each of the wires do (for your project) at the relay, so long as you pull power from the bus bar whether it be a juntion block (as in the case for 74 and others) or horn relay. that is unless you add more than the main alt wire can handle. use the headlight wires before they branch or are spliced to actuate the relays. you really need info on headlight wires more. got a haynes manual?

norvalwilhelm

You just need two 30 amp bosch relays and 2 30 amp fuse holders.
On the drivers side break into the wiring harness. Use the wire that normally activates the low beams, cut it, splice in the relay using only the trigger part of the relay. Now your low beams only activates the relay. Run a direct wire from the alternator to a 30 amp fuse holder and then to the relay. Take the other side of the wire you cut for the low beams and connect it to the output of the relay.
Now when you turn on the low beams you draw milli amps because you are just closing a relay. The alternator supplies 14 volts directly to the lights.
Do the same with the high beam wire. Cut it, splice the one end to the relay closing contact and the other side to the output of the relay.
It is very simple and the lights are much brighter and at the same time the old headlight switch and dimmer switch never see load so they will last forever. Also the fuse panel no longer handles the large amperage required to run the lights.
I run a complete post on this a few times.
It is a simple cheap modification.

jimmygmartin

This is really good information, how about headlight bulbs ?? Any suggestions ??

Eddie 70

I have said it before and I am going to say it again. This is one of those projects that I am going to do, I just got to get off my duff and get after it. The last time this subject was brought up, I posted a pic of the back side of my drivers side lower dash panel. The previous owner experienced first hand how much current the headlights really draw. It is enough that the headlight switch melted the dash pad. Not too good. Installing this mod will remove essentially the entire load of the headlights out of the car and to the relays and thier fuses. IF something goes wrong with the circuit it then blows a fuse and does not burn your car down.

This pic is my original dash pad, otherwise in good shape but look at the upper right side of the dash pad where the headlight switch should be. Bad ju-ju.

http://temp.corvetteforum.net/c4/edd...r_pad_rear.jpg

Eddie 70

Norvals original thread.

Eddie 70

Parts Express Bosche Relays

TXwayno

I may try to do this and also hook up diodes from the direction of the high beams triggers to the low beam triggers so ALL four lights are on when I click on the brights! I just done something like that on my Avalanche. Now when I hit the brights, the high beams, low beams, fog lights and drl's ALL come on at the same time. Buddy, you talk about lighting up the road!

cardo0

If u bring the wires over from the horn relay then the headlights will only work when u honk the horn.

Those Bosch relays should work but kinda over kill. Most H/L are 60W so 60W/12V = 5amps X 4 H/L = 20amps total for all lights. Try Radio Shack for 2 automotive 12VDC relays at least 20 amps each. Well those 30 amp relays look fine now - good guessing to u.

Now the reason u what to run realys is brighten the lights right? And they get dim from the lower voltage as the contacts in the switches and terminals age and corrode - creating voltage drops/loss. Try some #10 automotive wire at least or bigger (small cable ok) and run it from the batt itself up front to the new relays. I don't like the alt idea as it may create problems that take to long to type in here to explain. Such that the H/L is now wired with that #10 (or better) wire and the relay is switched by the old H/L wire from the light switch.

Try this for wiring that relay(s): Oops, i made a small drawing in paint but it won't paste inside here. Well send me your email address and i'll attach it to a mail to you - if your interested.

Hope this can help. cardo0

SIXFOOTER

Dude, read and heed the MAD Article. Running the headlights from the battery is just plain ignorant, sorry. The Headlights are run typically only when the engine is running right? So why ship the current for the lights all the way from the Alternator, to the battery, then back up to the front of the car for headlights? Makes NO sense. Run a #10 from the alt to a term block, from the block to the relay, and realy to the lights. Run the control for the relay from the original light cnnection to the coil side of the relay and ground the other side. Good to go and works better

I'm Batman

umm...the outside lights should be hi/lo, and the insides hi only.

TXwayno

Damn, now that you mention it, I think your right. I've been messing with the Avy to much it looks like.

norvalwilhelm

It is really simple to hook up the relays so the low stay on when you activate the high but I was afraid the bulbs would overheat. They are designed to have either or on not both so the added heat might just cook the bulb.