Double switched engine bay lights

Ok. Not sure if this has been done here and I apologize if theres a thread about it that I haven't found....

I'd like to wire in some under hood LEDs that are ran off a relay and switched with a tilt switch attached to the hood. That alone I think I could do. Here's the tricky part. I'd like to have a 3 prong lighted switch in the cab also. That way, if the tilt switch gets stuck closed, the lighted switch will illuminate and tell me it's on. Also, I'd like the switch in the cab so I can turn the lights off if I were working under the hood during the day for an extended period of time. The whole idea is to just keep the switch in the cab on all the time unless I didn't want them on and use it as an indicator to tell me if they were on.

I think I've figured out the diagram and was wondering if someone could look it over and tell me if it would work and more importantly, is it safe?



Thanks

Edit: the fuse on the positive side of the batt should be before the split.

 

It's safe and it'll work however the tilt switch would only make the toggles light come on if the toggle was left in the on position. Nice job.

 

Here's how I accomplished (mostly) the same behavior:

1. Instead of tilt switch: use a magnetic reed switch at the hood hinge.
2. Instead of indicator light in the cab: Use a timeout circuit that turns off the light after 4 hours, to prevent battery drain if the reed switch fails, or hood is left up indefinitely.
3. Instead of a manual cutoff switch in cab: Keep a little magnet next to the hinge. If I want the light off, I can set the magnet down next to the reed switch, as if the hinge was closed. If I want the light to stay on after 4 hours, I can swipe the magnet past the switch to reset the timer.

No thru-firewall wiring, no risk of draining the battery, and saves dashboard real estate for switches pertaining to driving. Also, a tilt switch might work incorrectly on steep inclines, or flicker during spirited driving, whereas a magnetic reed switch will be harder to fool.

That's just a suggestion though. Your approach should work. Whether or not the pilot light turns on with the tilt switch (or requires toggling first) will depend on which terminal is connected to the light internally. If the indicator light doesn't come on with the tilt switch, then swap the two positive wires on the switch, and it will.

Finally in my opinion, a relay is overkill. My hood lights draw about 150 mA and are by far the brightest and most useful underhood lights I've ever had. That's small enough current to be switched directly from even a wimpy reed or tilt switch. Skip the relay unless you're going to be using light bars or something crazy.

 

I installed an under hood LED light using a mercury switch. In five years I have never had a problem with the light inadvertently not turning off. The switch is adjusted so that the light turns off when the hood is half closed (I can see it turn off, and on, while opening and closing the hood)

 

I'm a proponent of the K.I.S.S. method and I agree with what @DG92071 and @mk5 said. I personally would want to keep the number of wires transferring power through the firewall to the lowest number as possible. What I would do is take @mk5 idea and instead of using a magnetic reed switch, I would use a Red Guarded toggle switch. Not all red guarded toggle switches are made the same, you'll want one that will turn the switch off if it is in the closed/guard down position. You could install it in such a way so that if the red guard is up, closing the hood would hit or interfere with the red guard so that you'd have to close the switch to close the hood. That way you'll have piece of mind knowing that if your hood is closed, the switch will be in the off position and it gives you control of whether or not you want to have underhood lighting based on ambient light level. You would wire it just like any simple SPST circuit.

-J

 

In keeping with the "alternative suggestion" theme I would use a mercury switch, no relay, no manual switch in the dash, no indicator light inside the cab, and an LED or two under the hood and that's it.

In my alarm installing days I've seen quite a few magnetic switches go bad but I never had to replace a mercury switch. I did install a lot more magnetic switches than mercury switches.

But probably the easiest solution of all is a factory Ford underhood light with a built in mercury switch, they only have one wire (power), and they ground through their mount. They're incredibly tough and work well.

 

Thanks for all the replies! I love TW school!

Having the toggle switch off should disable the whole circuit right? My leds shouldn't come on with the switch off. I'm looking for the toggle light to come on when the tilt switch is activated and the toggle is in the on position. Kind of like a tattle tell. Thanks

Yeah I've had issues with the magnetic switches on the past and am choosing to go with this mercury switch.

$6 ECS Normally Open/Normally Close TILT Switch

https://www.amazon.com/dp/B073HNMCMN/ref=cm_sw_r_em_apa_i_1GBmEbSN3X039

I hooked it up to my multimeter an shook it around like I was accelerating and decelerating violently and tried to make it come on in the horizontal position and I just couldn't. It does activate at about 10-15 degrees so if I were offroading up some serious inclines, I'd just have the switch there to turn it off.

I have decided I should scrap the relay as there really isn't a ton of amperage running these lights.

My 05 didn't really come with many options. All I have on the switch panels is my inverter and power mirrors. I have like 5 empty spots for a switch. I also ran a wire chase through the wire harness grommet going through the firewall for any future installs.

Never heard of a red guarded switch. I'll look it up right now.

That wouldn't give me the option to disable the circuit or give me a tattle tell to tell me if they are on. I may just trying to be too freaking fancy here but I've read many posts of guys dealing with dead batts not knowing their hood lights were stuck on for whatever reason. So that led me to 2 needs: a tattle tell in the cab (a lighted switch or an inline led indicator of some kind) and a way to disable the ciruit. A lighted switch does both of these.

 

https://www.sparkfun.com/products/9278

Something like this, but you'll need to make sure you get a switch that will turn off when the guard is down if you decide to go with this route. Also, you'll probably want to find a water resistant toggle switch from the boating industry, usually they will come with a rubber condom over the switch base plate. This is merely one option.

-J

 

Ah yes the ol missile switch

 

https://www.westmarine.com/buy/blue...43725&cm_sp=Onsite-Recs-_-DY-_-Search-Results



or

 

Bingo, it has the ability to behave like a momentary switch if you were to close the hood causing the guard to close and turn off the light, as well as give you control on activating your lights. Simple switch, relatively inexpensive. Plus, you can sticker the switch to say 'Fire Ze Mizzilez!' and instantly gain 2 cool points.

https://www.westmarine.com/buy/blue...ches-spst-spdt-on-off--P014122402?recordNum=7

-J

 

You could also use a pin switch that activates with the hood.
The easiest way I can think of is to wire up the lights and use the pin switch to switch ground to turn them on.
The physical switch will make sure they don't turn on when the hood is closed. Eliminating the need for a switch or indicator in the cab.

 

I was definitely considering a simple ciruit with the pin switch at first until I read a few threads about dead batteries due to failed switches (stuck on ground and slipping out of alignment). I get it that the tilt switch is just more of a luxury thing I thought would be cool . I know there's much simpler solutions. I dunno maybe I'll just go with a missile switch or something...

 

A simple indicator like that would be nice though

 

What would be wrong with a simple switch under the hood that turned the on and off....

 

Just a rocker switch? It might get left on. If it's a pin switch, I've seen many that have failed or slipped after some off roading. The missile switch is a good compromise because you manually turn it on and it automatically switches off when the hood is closed. I guess I find myself taking others ideas and building on them. I'm not embarrassed to say I wanted a mercury (tilt) switch because it's cool lol. Just dont want it failing also and the lights staying on after I park my truck and not noticing.

 

Why not a pressure switch that is inline with a toggle / rocker switch in the engine bay. That way if left on the pressure switch disconnects the circuit, and if the pressure switch for some reason fails and makes the circuit live (have you ever seen a pressure switch on a door of a car fail???) then the rocker switch will be off more than likely so lights wont turn on.

Also if you do lighting right under the hood, you would easily be able to see them on while the hood is closed.

Last point, just get a headlamp, cus really how often are you under the hood for any length of time on a toyota?

 

Yes the toggle switch would ensure the LED's aren't on unless the switch is on.

As long as your happy with the end result OP that's all that matters.

Idk why I didn't think of a pin switch option lol. My head must have been stuck on the mercury/magnetic thing. Typically hood pin switches are set up so the hood has to be significantly raised to turn on a light. Pin switches on hoods for alarms must be set up more tight and are problematic because of it.

While we're on the topic of working under the hood you should look at hydraulic struts for your hood. I got mine from Striker Ind. Gets rid of the requirement of using the hood prop rod and stops the mechanic from getting his head bashed with a hood. Lol