EFI 3 vs INJ fuses

I initially connected my Raptor style grill lights with an add-a-fuse to the EFI 3 fuse. The lights were on whenever the ignition switch was on. Just like I wanted .

I'd read that EFI 3 would turn back on for an emmision test after 4 hours. Sure enough, about 4 - 5 hours after shutting down the engine, the lights came back on. I'm not sure how long. They turned back off while I was thinking about it.

It "appears" that the INJ fuse will perform like the EFI 3 fuse, except NOT turn itself back on for an emmision test. So I've moved my add-a-fuse to the INJ fuse .

Can anyone confirm how the INJ fuse works? Is it only hot when the ignition switch is on?

Edit: If it matters, I have a 2019 SR5 V6.

12/4/20 Edit: This information applies only to the V6. Study @caribe makaira 's post #14 carefully to figure out WHY. Post #45 shows it more clearly. Thanks Caribe!

 

I’ve had my lights hooked up to that same EFI fuse and always wondered why the lights came on. Good to know. Nervous for a short to blow a fuse or something in my EFI OR INJ system so thinking about somewhere else to tap into currently

 

I would recommend getting a schematic and wiring diagram for your truck to confirm before randomly connecting to fuses.

 

I'm game. Would you happen to know where I can find them? I haven't had much luck searching for them.

 

TIS, $20 for a 3 day membership. Gives you access to all the wiring, the FSM, any open TSBs. You can download them all for future reference.

https://techinfo.toyota.com/techInf..._US&resource_url=https://techinfo.toyota.com/

 

Thanks. I'll check 'em out.

 

I decided to leave the add-a-fuse on the INJ fuse. Its working like I wanted it to. The lights only draw 0.160 Amp. I'm happy.

 

quick question does that add a fuse protect the INJ fuse from the raptor lights? is that why theres two fuses on it?

 

I've been trying to do the same thing you did but the only INJ fuse I see is a 20 amp, is that the one you're using?

 

My INJ fuse is a 10 amp. The add-a-fuse for the grill lights is a 5 amp. Heck even a 1 amp would be big enough for my grill lights. They only draw 0.160 amp. If something goes wrong with the grill lights, that fuse should provide isolation from the INJ circuit.

 

Yes to both questions.

 

So weird, we both have SR5 as well. I'm gonna poke around some more, but do you see a reason why it would not work for me to use the add a fuse in that slot with a 20a fuse for the INJ and a smaller fuse for the lights?

 

I'd check the layout drawing inside the fuse panel cover. Use whatever size it calls for as your INJ fuse. Then a smaller fuse for the lights, like you said. I've got a 5 amp in mine but plan to change it to a 1 amp.

Edit: I couldn't readily find a 1 amp low profile fuse. I did find a place where I could order 100 of them, but had no idea what I'd do with the extra 99.

I WAS able to find a 2 amp fuse, so that's what I'm using. Realistically, the 5 amp fuse would have been fine, but I feel better with the 2 amp.

 

Thanks for posting the schematic Caribe.

It still doesn't completely answer the question though, because it doesn't show how and when the relays are energized.

However, I've been using the INJ fuse spot for over a month now, and it does APPEAR to only turn on whenever the ignition switch is on, like I wanted.

 

Engine ECU at ignition. Not always "hot".
Down "stream" from IGN sourced 10 Amp INJ fuse:

 

I should mention that the add-a-fuse/circuit in the pic is inverted, adding a fuse after the Inj fuse, not in parallel with it. They do sell "left" facing add-a-fuse but I don't know it it'll fit.

 

Im curious, and prefer a yes/no answer. Is there a problem with using add a fuse off the INJ fuse?

Is yes, please explain why in layperson terms! I genuinely want to learn and understand, but I have to understand

 

As long as the additional load is small, there should not be a problem. Altogether, my 4 grill lights (which have 3 LEDs each, for a total of 12) draw "about" 1/2 amp. It's been a while, so I don't remember exactly. I was going to use a 1 amp fuse for them, but ended up using a 2 amp because of availability.

My lights are on anytime the ignition is on, and they haven't been a problem for the 6 months that I've had them.

EDIT: I read back over some of my old posts in this thread, and found the number that I couldn't remember earlier. My grill lights draw 0.160 amp, so it's way less than 1/2 amp. That was measured with a multi-meter back when I first installed them.

 

Thanks for the quick response!