Headlights Relays In Absurd Detail

Hot diggity dog! What a complete article! This is the sort of detail that needs to be available to every project. Huge thanks to Tim!

Guess that I will set my headlamps up with relays before I plug them in.

Opinion time: Do you suggest putting relays in for the backup lights? Do I want to run full voltage/amperage through my transmission's Neutral Safety Switch? And for DRL circuit - same thing? The headlamps I am looking at have a DRL "angel eye" function that lights up when the key is in RUN position. Even though this is an LED function, I am pondering a relay here, too.

 

You can relay most any load to reduce the draw on the switch drl is a good use key on =drl

 

Excellent write up Tim thanks.

 

Thank you for the excellent tutorial.

I’m intrigued by the sealed beam to bulb conversion kit you referenced. I may have to give it a try.

 

You can always slave a relay to another switch. The relay coil only takes about 150 mA, and that's a low load at these voltages. I would decide based on the competing factors - potential increase in reliability (not clobbering the switch with a bigger load) versus additional complexity. Realize that anything electromechanical - switches, relays, connectors - have their own reliability issues and a finite number of cycles and lifetime. An indicator bulb is a pretty light load, LED or incandescent. If I wanted actual DRLs, I would use a relay maybe connected to an oil pressure switch? Then the DRLs would be on only when the engine is running.

 

The 6024 is the standard bulb for these 7" lights, and the H4-powered 6024s have been around for a long time, at least 50 years. For much of that life, the market was dominated by Cibié (see-bee-ay) and Hella. Today the halogens are old stuff, and LEDs are popular. Back then, the law required "sealed beams" and some companies made (still make?) sealed bulbs with a halogen element, to get around the law. The law has changed, and the H4s are legal if not too bright and an approved reflector. I know nothing about the LED bulbs and reflectors, but there is a lot online about them.

 

Couldn’t you use the normally closed part to energize the drl and have the headlight relay pull the drl relay off when the headlights come on? This is how we feed high and low beams at the same time in high using three relays.

 

Sure, that makes sense. Not that much experience with DRLs - my VW and the KL, which I'm sure has some fancy computer-controlled algorithm. Possible it does not have DRLs - I will now have to pay attention to what it does. The VW DRLs come on when the ignition is on, which I always thought was kind of dumb, putting the lights in parallel with the starter motor. There is also a light switch, which must be on to get either the fog lights or high beams. You can, however, drive all over town at night without turning the lights on.

 

Thanks for sharing Tim.

 

I can't say what the intermediate Jeeps use, but the early models (at least in the '60s) have either a glass fuse or a circuit breaker mounted on the back of the light switch. The hot wire that feeds the switch attaches to the fuse holder/breaker, which then feeds the switch itself. This is typically the only protected circuit on the whole Jeep.
From the factory, the wires leaving the switch carried the full electrical load to the lights (or dimmer switch). Tim's updates using relays make the original wires only carry switching (lesser) loads.
-Donny

 

I have to check and see how the LED unit handles the DRL, as they also double (with a color change) as an extra front facing turn signal.

Dunno if I'd want to link the DRL with the low beams. If I did, then the DRLs would come on when the lows kick off and the highs kick on, right?

 

That is what I was remembering from from looking at the light switch on my 64 3b I had in high school. Thanks

 

Maybe we aren't talking about the same DRL. To me, DRL is "daytime running light" and it means that the headlights are on in the daytime. Is that what you mean?

 

typically the drl turns off with any head lamp high or low

 

These headlamps have a main low-beam and high-beam capability. Around that, there's a halo that is white to handle Daytime Running Lights, and that turns amber into a turn signal.

I haven't purchased them yet, but I presume that there are four circuits involved in the package. There'll be one for Low Beam, one for High Beam, one for the DRL and one for the turns.

And I understand about the concept of DRLs using the main low-beam (but sometimes at a reduced output), but this set isn't like that.

PS: I leave this up to the moderators if they want to split this DRL discussion out of the main sticky thread regarding relays. I do not want to clutter up Tim's perfect explanation with my issues (unless you feel that it does fit in here).

 

The factory headlight switch from 1974 and later Jeep models all have the circuit breaker built into the switch.
This would be the GM type of switch, that has the big plastic plug, and also has the dimmer switch for panel lights built in.
The type of headlight switch I'm talking about is the unit where you have to push the button on top of the switch to remove the headlight switch knob and shaft.
Just an FYI.

 

Huh. I remember the earlier switches have a circuit breaker on the outside of the switch. With the newer style, can you see the breaker from the outside? It's not noted on the circuit diagram, and nothing in the electrical text that I can find. Not doubting ... it makes sense there would be something besides the fusible link in the light circuit.

 

Actually, Jeep started using this type of headlight switch in 1972.
I suppose easiest way to tell is to rotate the knob and shaft, it should turn easily and control bright/dim of dash lights.

 

Not doubting the existence of the circuit breaker, just wondering if there is external evidence. The switch on my CJ-6 definitely has the skewer knob and release button. I've replaced the knob.

 

Awesome thanks for putting this together!

Back in the day I put a 100 watt high beam bulb in my Sportster and learned about the melting point of the push on socket plug a few nights later