Wiring- How many amps blows a DRL fuse?

I'm currently working on a facelift of a 2013 Limited to a 2014 Trail. One of my road-bumps is if I tie in the drivers and passenger side DRL, to 3 "raptor lights", and both "backlights" on my SS3's, will I blow a fuse? I could make a wiring harness real easy.

 

What are backlights?

 

https://www.youtube.com/watch?v=mEaikdMvdHo

 

Don't the highbeams double as DRLs, just with less power?

Please don't use T-taps.

 

2010-2013 the front turn signals are also the DRLs. 2014-2020 the high beams are the DRLs but dimmed via PWM. 2022-2024 have a dedicated DRL. 2021 has some trims with PWM and some with dedicated DRL.

For OP, you’ll likely end up with your backlights and raptor blinking with you turn signals

 

Here we go. DD recomends wiring to the DRL wire. The current draw is .4 per backlight, so call it 1.0 amp. I wonder if this will throw the 2013 into turn signal mode. I will be using 2014 specs. There must be a threshold burried in some engineers desk. I might have to just do the wiring with a relay. I was so hoping I could spimplfy things. Or, I could experiment. I'll have the entire bumper appart.

 

The DRL/front turn signal combos are on a 15A fuse. It’s still a single bulb though which means both the DRL function and the turn signal function go through the same wire. The extra draw isn’t going to trigger turn signal mode - that’s all done at the turn signal stalk. Backlights you could tie into their respective sides and they’ll blink with the turn signals. You’d have to split the raptor lights (hard to do with 3 of them) and have half attached to left and half attached to right. Or get a latching/timer relay to run the raptor lights

 

I never said I wanted the turn signal tied into the DRL. There are speprate lights run. One is for Turn signal/ DRL, the other is for DRL only. So one bulb is 21W (single filament) and is on all the time when DRL is chosen. That's all it does. DRL on or off. The other 21W bulb (single filament) is the turn signal/ DRL. When DRL is on, this 21W amber bulb comes on and is interupted with a blinking signal. When DRL is off, the signal only flashes. All I really wanted to know is how much current drain will blow a fuse. Can I tie in the backlights and raptor lights together? I saw a Yoda Exp where that is exactly what they did. So it will work, but that still leaves the question. To tie the DRL to the backlights and raptor lights would be the right way, but i'm worried about the draw.

 

Hi @Kezin. I’m fumbling with a wiring diagram from 2010 that I’m still learning to decipher. What is that 15 amp fuse labeled? My interpretation of the diagram is that the turn signals are fed through the Main Body ECU. That ECU has 4 fuses going into it:

10 amp ECU-B
10 amp ECU-IG N°2
7.5 amp ACC
25 amp D/L N°2 (D/L = door locks)​

I don’t know whether my diagram applies to OP’s 2013 vehicle, and if it does, which of the 4 fuses applies to the turn signal. Any clues?

 

On the stock vehicle a single 15A fuse labeled "TURN & HAZ" powers the front turn signal lights in both DRL mode and turn signal mode. Rear turn signals and side view mirror turn signals are powered from the same fuse.

 

Very good. Now I know where to look. I know that fuse. My best guess would be that this fuse could handle the overhead with room, but not much.

 

I’d have to see what light you’re talking about because on a stock 2010-2013, there’s only one DRL per side and it’s combined with the turn signals.

 

@3JOH22A is correct. It would be much easier if Toyota included all the relevant wiring in one diagram but they make you hunt for it. I posted a snippet of the headlight wiring which includes the DRLs for 2010-2013. It’s a single ground wire that goes to the flasher relay to trigger steady brightness. Then you’d have to go to a completely different wiring diagram to get the full story. If you look at the turn signal and hazard wiring diagram, you’ll see that there’s 3 fuses going to it. 30A towing that powers the trailer turn signals and brake lights (other lights as well but on different modules and not included in this wiring diagram), 15A turn&haz that powers the vehicles turn signals, and a 7.5A IG1 that is just the ignition trigger telling the flasher relay the vehicle is on and that it can activate the turn signals. Knowing the headlight wiring diagram shows the DRL trigger going to the flasher relay and output being on the same pins as the turn signals, Toyota leaves it to the reader to deduce the DRLs are powered by the 15A turn&haz fuse.

 

Actually the SS3's pull 0.4 Watts each, approximately 30mA per unit not 400 mA...so total draw for two units is well under 0.1 A (approximately 60 mA)

As a reference, my two SS5's draw just under 0.5A combined for the backlights and the SS3's are a four emitter unit compared to the SS5's with nine emitters.

SS5 backlight

 

Very well, I can obviously tie three raptor lights plus two SS3's without issues. I will wire the leads so I can disconnect the fog lights and the seperate backlight at the same time. As for the raptor lights, they will disconnect at each light. Simple and no need for a relay. Thanks photon chaser, and thanks guys.

 

A fuse will only carry 80% of it's rating continuously. Any more than that and it will eventually blow. How much you go over 80% determines how long until the fuse fails, the more load the faster the fuse blows.

Fuse curves don't lie. That's why engineers use them to size fuses...

 

Random short enters the chat...

 

Title of thread:"How many amps blow a DLR fuse?"

What's your problem?

 

So what you’re saying is that when adding extra electrical loads to a circuit you shouldn’t bump up against the fuse’s nominal value, but rather 80% of it? In this case: 15amps x 0.8 = 12 amps. Is that what you’re saying?

I remember back in the days of glass fuses one could opt for fast-blow or slow-blow.

The use of jargon without any accompanying explanation will tend to alienate the reader. It sounds a bit smug.

 

Fuse curves are used by engineers to size fuses. That is the correct way to ensure they are fit for purpose.

Sure, you can take a guess and maybe you'll be OK... or maybe not.

Would you allow a mechanic to rebuild your engine without paying attention to the manufacturer's specs? "Ah, piston to cylinder wall clearance is about an 1/8 inch, give or take..."

Why would you do that electrically?

Do some reading. Find out what fuse curves are. Then you can talk sense...

 

Sounds like a good argument to never tap into factory wiring. Or to never vary from manufacturer recommendations for oil viscosity and oil change interval. Or to alter ride height or wheel and tire size.

And I think OP’s question is beyond “taking a guess.” He’s at least trying to do the math.

So, never put more than a 12 amp load on a 15 amp fuse. Is that your assertion?

 

Yes, if you want the fuse to last until a fault occurs.

 

Interesting. I would have thought that 20% buffer would be incorporated into the rating.

 

Every wire I can see worth a bother seems to be able to handle 30A regardless of the fuse value. I'm not ever saying to go over the set value. I don't think the current draw on these lights amounts to a hill of beans.