Fuse not getting power

Following up on my post from yesterday:

https://www.tundras.com/posts/2724907/

I managed to figure out that the interior fuse labeled “PANEL” is not receiving power (neither terminal lit up when using a fuse tester while truck was running), and it seems that through this fuse runs the power to several (but not all) of the components that I mentioned are not working. Also, however, AC power runs through this fuse and AC is working fine.

Anyway, what to do next now that I’ve identified that this fuse isn’t getting power? (The fuse itself looks fine upon inspection.)

Frustrated here. Thanks y’all,

jason

 

you may have to chase wires to see where the damage is.... either a rodent got to them or they were shorted out somehow...

 

Hmm, thanks. I was kind of afraid of that. :-/

 

It is powered directly from the main fuses at the battery. Did you get a voltmeter and triple check you have not voltage on either side of the fuse? IF the Tail Relay is not closing properly it would not send voltage to the Panel fuse.

When you say the AC is working what do you mean? The control panel lights up? The blower fan is running? I dont see where the 7.5A panel fuse is tied into any of the AC circuits.

 

I read your original post, first of all what year is your truck?

You said a 3 Amp DRL Fuse was replaced with a 10 Amp fuse which started all these problems. I only see a factory 7.5 Amp DRL fuse in the engine fuse box, no 3 Amp.

Can you explain a little more of what you did vs when these issues started happening? That would help me be able to narrow down what went wrong/where to start looking.

 

Thanks so much for your help, Jeff. I am using the Morimoto LED headlights for my 2016 Sequoia, which come with a wiring harness for the DRLs that goes straight to the fuse box and clicks into the 10amp IGN location (39). This Morimoto connector comes with two fuses, a 10 amp and 3amp. The 3 amp fuse blew about 3 months after installing the headlights, which I discovered because the DRLs stopped working. Folks here suggested that the 3amp fuse should be relaxed with another 10amp, which I did, and the DRLs are working again. But now all the other issues have started.

Hope this helps! Also - how do I know if that relay you mention is bad? How do I test it?

Still learning here…. Thanks!

jason

 

Also - everything on the AC unit is working—blower, cooling, etc. I mentioned the AC because the manual says this interior fuse that isn’t getting power controls that too (see attachment). But there are other systems that don’t work that aren’t listed under that fuse, e.g., the auto power steering wheel tilt (this may because the computer doesn’t remember the position, though) and the clock resetting to 1:00.

 

Do this first, remove the aftermarket LED wiring harness completely, but in a 10 Amp fuse in place the way it was prior to headlight installation. Then check the 7.5Amp panel fuse under the dash. Make sure you are properly checking for voltage, a voltmeter is best.

Report back if this temporality restores power to the panel fuse.

I will start to look for links between the 10A IGN fuse and the 7.5A Panel fuse. We need to be very sure both legs of the Panel fuse have no power currently.

 

Thanks so much - I’ll try this in the morning and report back!

 

The main purpose of the 7.5A Panel fuse is to power the illumination lights to the Radio, AC controls, all dash buttons ect.

When you turn your headlights on have all your buttons, AC, Radio controls lit up as well? If so the panel fuse is working properly and has no issues.

All of those systems are listed under the panel fuse because they all have interior lights to that come on at night with the headlights on.

If you have not figured it out yet, I am still not 100% convinced your 7.5A Panel fuse is not working correctly. IT might not be but its very important to be absolutely sure it have no voltage on either side from the start. Or else we could just be looking in the wrong place.

As I mentioned if your dash button, Radio, AC lights have always been working, your problem is not the panel fuse.

 

DUH it just hit me.......

You will not have power across the 7.5A Panel fuse unless the headlights are on. When you turn the headlights on, it closes the Tail Relay shown above and powers the panel fuse.

I bet when you checked it with your tester the headlights were turned off so you think it has no power. Try testing it again with the headlights turn on and I bet you get 12v on the panel fuse.

As far as the other issues I would bet it is linked to the 10A fuse the aftermarket headlights are plugged into. I will keep looking into this.

 

Thanks Jeff. You’re right, I tested with the headlights off. This morning I’ll test with headlights on. And yes, all AC lights were working too.

Another trend I’m noticing - pretty consistently, at first crank in the morning all systems work perfectly. Just happened. Also stopped for gas and restarted and still working. If things go per usual, everything we fail again later today. I’ll update…

 

Update @Jeff_5_7 - I only drove the truck once yesterday and everything worked fine. Started it up this morning and all systems were online. Drove it to my sisters' house about 20 minutes away this afternoon, all systems fine. Started back up to head back home about 4 hours later and same systems were now not working again. When I got home I did test that one fuse with the headlights on and, as you guessed, it had power on both sides. So, that fuse is not the problem.

Another possible clue: I can now tell when the systems are not going to work even before I start the truck because my cabin lights won't work, my keyless door unlock won't work, and I can't open the back hatch. So, it seems like whatever the problem is, it kicks in while the truck is NOT running. I've never been driving and have the systems stop working if they are working, or start working again if they were offline. Curious if that gives any more clue here...

And one last thought - as I mentioned in my other original post, this all started after I switched that 3amp fuse for a 10amp in the aftermarket DRL harness, but the first time I tried to do it the truck was still running . So I'm wondering, did I screw something up then? Could pulling that IGN fuse while the truck was running have screwed something up downstream, like a relay or something - that sometimes still works and other times doesn't?

Still pretty stumped,

Jason

 

CRAZY UPDATE! So, chasing my logic about the systems not working when the truck is OFF, I found which fuse should be receiving power in order for things like the door lights and cab lights to work while the truck is off - and that's fuse 34, the DOME fuse. So, I opened the door with the truck off--no cab lights coming on--and tested both sides of fuse 34 and, sure enough, no power. BUT - when I touched one side of the fuse I saw a little spark at slot 30, which is labeled blank in the book but there is what looks like an interior fuse (shorter metal tines) in that slot (no number on it, so is this even a fuse, I don't know?). Anyway, I pushed down on it and VOILA the interior cabin lights came on! I started the truck and all systems were back working again. Turned the truck off, wiggled that fuse/plug/whatever is in slot 30 and I got the cabin lights to go off again. Pushed back down on it and they came back on. So, this thing in slot 30 appears to be the issue. Is this a fuse? Do I need to replace it since it seems a bit wiggly? I've included a photo and circled what is in slot 30.

 

That's really odd.
Did you buy the vehicle new or used?
What is that add a tap powering?


Fuse Box Diagram Toyota Sequoia (2008-2017) (fuse-box.info)

 

Looks as if that fuse has been replaced at some point with the incorrect size fuse. I think I’d find the right size mini fuse and replace that fuse for a better connection

 

Its not a fuse, its a "jumper" called a short pin. Its essentially a "plug in" jumper to connect the battery to some of the systems of the truck. Found online "Short Pin that when removed from the Truck it disconnects part of the electrical circuits that could drain the battery during storage and shipment." Apparently these are removed when shipped from the factory and reinstalled by dealers before selling to keep the battery from draining in shipment.

It connects the battery to the 30A AMP, 20A Radio, 7.5A ECU-B1 (Door locks, Power Seat, Power Tilt Wheel, are on this circuit), and 7.5A Dome fuses shown in the red box below. You can see where Toyota calls it "Short Pin" in the diagram and fuse box layout.

 

I took some photos of an extra engine fuse box I have laying around. As you can see the short pin is clear but has no number on it like the 25a clear fuse above it.

I pulled both out for comparison. As you see the short pin doesn’t have a fuseible like between the pins, it’s solid.

I would pull yours all the way out and make sure it’s clean getting good contact. Mines dirty and corroded, not good. I’m sure you could get one from the dealer or auto parts store for a few bucks. Might call around and check. Hopefully this permanently fixes your problem.

 

Just for more FYI, the Short Pin essentially connects the top section (Green Box) of the fuse box to the bottom section (Blue Box) of the fuse box. With a bad connection or a removed Short Pin none of the fuses in the bottom blue box will have power. Your Dome, Radio, ect fuses.



As stated above I would clean yours and make sure it is seated in the slot frimly with good connection on both sides, additonally find and buying a new short pin could be a good option.

 

Thanks @Jeff_5_7 and others! This is really helpful. I do think my jumper pin was a bit corroded so I will certainly look to replace it. You guys have been great!

Incidentally, @Jeff_5_7 where are you finding those more detailed fuse/wiring diagrams? I’d love to know where to find those for future reference - thanks!

Hopefully others will find this thread useful in the future. What an odd and obscure fix to this problem—that one little pin controlling power to so many systems!

 

Here: https://www.tundras.com/threads/ultimate-wiring-diagrams-collection.81448/

You can thank @RainMan_PNW for downloading the official EWD (Electric Wiring Diagrams) from Toyotas TIS (Technical Information System)

Everything I posted has been from 2014-2017 Tundra diagrams which is essentially the same as the Sequoia. It won’t show things like the back hatch or things more specific to Sequoia only but it’s close enough.

Additionally, anybody can register for the Toyota TIS website, $20 gets you access for 48 hours and you can download almost any Toyota document for any model.

If you want official 2016 Sequoia Diagrams, Repair manual this is where to get it. Unfortunately you can only print small sections to a PDF at a time and merge it all into one document. So be prepared to spend a few hours to download an entire EWD of Repair manual.@RainMan_PNW may have some tips on this as he has done it all for us in his post above.

 

I learned something today..
I had no idea this existed.

pg015l02 (toyota.com)

I wish I had my Tundra here so I could go look into the fuse box..


Could he just use a large amp rating fuse for now?

 

Theoretically, you could jam a paper clips in each leg and it would work. You just need somthing to close the air gap in the ciruit.

So yes, a large amp mini fuse could work for a quick fix. However I am not 100% sure the fuse would slide in the slot and firmly seat. Look at the photo above with the short pin and fuse. The short pin looks like very close housing wise (plastic grove line up marks ect) to the fuse so a fuse might work.

 

No additional comments other than be organized and make sure you click through EVERY link - some things (like the connector positions) are several pages and printing/downloading only gets one page at a time.

I’ve never attempted the service naturals because those suckers are HUGE…