Hi/Lo Beam Relay Wiring Question

[fords4life]

Pretty sure there a couple of you on here who are smarter with electricity than I am.  I going to be doing the headlight relays as I put everything back together, but I'd also like to wire in the Lo beams to stay on with the Hi beams.  I think I have the relays setup correctly, but please provide feedback if it doesn't look correct.

[Gary Lewis]

I’ll have to sit down and draw it up, but you should only need two relays. One brings both low beams on with the light switch, and the other brings both high beams on from the dimmer.

Will be later before I can do that though

[Gary Lewis]

This isn’t pretty, but I think it will work. When the headlight switch comes on the low beam relay comes in. When the headlight switch is on and the high beam has power on the dimmer has power the high beam relay comes in.

[fords4life]

Gary - Edit.  I think I got it.  You're pulling power from the headlight switch like I did, but it constant powers the low beams, when you hit the switch on the floor boards, the highs are going to come on, but it doesn't affect the lows.  Duh.  Sorry, I misread it the first time.  This is why I post my crazy ideas.  I always try to figure out the hardest way to do it. lol

Thank you.

[Gary Lewis]

[ArdWrknTrk]

Careful you don't vaporize the filaments.
50+60=110W of heat needs dissipated.
That's a lot more than either alone, in one small glass ampoule.

I used to do it with my old Datsun, but that had four lamps, so it was no different than having either one on.

[old55pete]

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[ArdWrknTrk]

Because the headlights and incredibly brighter, and taking that load off the dash harness means the switch can handle the backup & tail lights without melting the wires in the plug.

[Gary Lewis]

Yep, Jim is right. The wiring and switch were marginal when new, and are now far from new. So installing a relay harness is strongly encouraged. And not only does it take the load off the wiring and switch, it delivers higher voltage to the headlights so they are brighter.

And to answer your question, it is something you should do. But you can buy a headlight harness from LMC, Jeff’s Bronco Graveyard, etc so you don’t have to make one.

[kramttocs]

Another vote for doing this. My truck was already wired with the relays when I got it and there is a noticeable difference in the light output between it and the 80. Also the pulsing at idle is a non-issue.

[Gary Lewis]

Wired per my latest diagram, which has the low beams on with the highs? Interesting.

[kramttocs]

No, edited my post immediately but not before you got notified. They are just the typical relayed setup.

Was actually discussing this with a family member earlier and since it's on the relay topic - fords4life, how are you doing the fuses?


Inline
Relay with built in blade fuse holder
Multi relay/fuse block
?

[old55pete]

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[Gary Lewis]

Yes, I use the auto-reset circuit breakers. But I wouldn’t worry about the tail and marker lights. The switch can easily handle them with the headlights off of it.

[Nothing Special]

... and as an indication of how much it can help, when I put relays on the headlights of my son's '01 Jeep Cherokee the voltage (with the engine running) at the headlight went up to 13.6V from 10.4V!  That's a 74% increase in wattage!

[ArdWrknTrk]

And given that most bulbs are rated at 14V so they don't constantly blow out that's saying a lot, given inverse square law.

The output must have increased dramatically

[old55pete]

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[ArdWrknTrk]

Plug-n-play is a nice feature when it's done right!

You still need to run the ground wires.
I use SDST 8x1/2 hex head zip screws to the radiator support. (because that's where my negative terminal 8 Ga. auxiliary ground goes)

[ArdWrknTrk]

I have a kinda neat Hella twin relay in the bottom of one of my 12V  boxes, along with the random lugs, relays, chunks of harness....

When I get back to the barn I'll have to dig it out.
It is what I used to cascade my Datsun headlamps back in the day.

You could wire a relay, 87A to an SCR to latch the lows, then use 87 to energize the highs.

[Nothing Special]

ArdWrknTrk wrote

And given that most bulbs are rated at 14V so they don't constantly blow out that's saying a lot, given inverse square law.

The output must have increased dramatically

The Cherokee was mostly driven by my (at the time) 17 year old son.  One night I was replacing a U-joint on the Cherokee so he took my wife's Ford Escape to work.  When he got home he said that he thought the Escapes headlights must have been on high beam, but once he figured out how to switch them found that they were on low.  So was there anything we could do about his headlights?  I drove it at night to see what they were like, and it seemed like it was just running the parking lights   So yes, it was a dramatic improvement!

It did burn out some headlights after that.  I put new lights in it when I did the relays because the old ones were a little corroded on the terminals (which didn't help the light output either I'm sure) and both of the new bulbs burned out within a year.  But both of the replacements I got when those went were still going strong about 4 years later when we traded the Cherokee in.  I'm sure the higher voltage was a factor in the short life of the first set, but I think poor quality bulbs was also likely a factor.