Half of fuse box not working!

So my story begins the other day when I noticed my battery gauge was low, so I checked the voltage, and it was high 11s while running and slowly dropping. I replaced alternator. Now, the truck will start just fine, but my brake light, abs light, and traction control lights are on and quite a number of things dont work. (INCLUDING PUTTING INTO GEAR!) Which makes life very difficult with a truck that will run but cant move lol
I've checked and replaced just to be sure every single fuse in this entire truck multiple times, in the cab and under the hood. Everything is fine except for half of the cab fuse box. If you look at the picture it would be the entire left side of the fuse box. One weird thing is, the new alternator is not putting out 13-14 volts, but at low 12s right now, matching the battery, which makes me think the alternator is also still not working. Would a bad alternator or alternator fuse make half of this fuse box not work? I've looked at wiring diagrams but am having a difficult time understanding the link between the two. I've searched all week for answers on my own and have not found any, which is why I'm here now. Any help would be greatly appreciated! Thank you guys so much

 

Found this thread - not sure if anything there would be of some help.

Alternator not Charging | Toyota Tundra Forum

 

Thanks for that just read entire thread and saw that many people are having the same issue as me but did not see a fix

 

Welcome to the forum.

I have no idea what is wrong, but I did make an observation;
The fuse box is upside down from the diagram, so it is everything on the right side of the diagram that doesn't work.


Everything on that side depends on a triggered relay to have power.
So they will only have power with the IGN or ACC on and they all run thru the IGN switch.
I doubt all your relays are bad, but it seems something has stopped them from activating.


Perhaps you could do some testing at the IGN switch?

Good luck..

 

Thank you for that diagram, I have just taken apart everything inside the ignition. Previous owner had a viper alarm and remote start installed, so I just deinstalled it and spliced all wires back together how they were from the factory, still to no avail. I'm not exactly proficient in reading these diagrams, but where on there does it say where the power comes from the ignition back to the fuse box? and what color wire? If i know that i may be able to do some continuity tests and go from there. Thanks again for all your help

 

You can find your diagrams here. Ultimate TUNDRA Wiring Diagrams Collection | Toyota Tundra Forum

Keep in mind I'm not a mechanic, I just dabble in trying to help people.
Perhaps when he has time @RainMan_PNW could take a look and give his input.
He has a pretty good grip on reading diagrams.

Does every fuse on that side of the box not work, including TAIL and PANEL?
Do the parking lights and dash panel lights not work?

The black wire on top of the page provides power to the fuse box, which is why one side works, there are no relays..
On that side everything is straight from the battery thru one of the main fuses.
It also provides power to the other side of the fuse box once the 5 relays are engaged.




Here is everything on one page.


The ignition switch.
Since the truck starts and runs the lilac wire on pin 5 has power.



From the ign switch;
The white wire pin 4 engages the TAIL relay for the parking and panel lights.


However I'm confused about why it shows a connection of the black and white wire circuits between the AM1 fuse and the relay.


The beige wire to the fuse box;
Pin 2 grey wire from the IGN switch then beige after the ACC Cut Relay engages the ACC Relay





The lime green wire pin 1 engages the other 3 relays, IG No. 1, IG No. 2, IG No. 3 to the remaining fuses on that side.



Make sure when the key is on, all 3 of those wires have voltage at ht IGN switch..

Also all these relays have the same ground point except the TAIL relay.


I'd guess all I am doing is making it more confusing, if so sorry about that.
Again, perhaps @RainMan_PNW has some input when he has time.

Good luck..

 

Well, I am trying to keep up and I really thank you for putting this work into this for me. So in short, when I start the truck, I should be checking for 12v at the lime green, beige and white wire at the relay?. Are these the relays inside of the fuse box under the hood? It seems counter intuitive that they would go from the ignition to under the hood, then back to the in cab fuse box. I wonder where that J78 junction connector ground wire is located.? I will keep plugging away at this, and hope I can find something. I'm pretty mechanical but this electrical stuff is throwing me for a loop. Thanks again.

 

So just trying to wake this thread up, I've replaced the main 140 amp fuse to no avail. Still no power to half the fuse box. I've done my best to trace ignition wires to see if there was a break anywhere and did not see any. Does anyone have anything else that may help?

 

I'd like to know where that one grounding wire is. I've looked around and I don't know where it could be, that may be the issue

 

I don't think that is it because it connects to 2 other grounds.


If you can find the DD connector, test pin 62 and see if has a ground.


But here is all 3 of them.


Did you have power coming out of the ignition switch to the lime green, grey, and white wires with the acc/ign on?

 

The main fuse will not be the problem. If it was none of the fuses would have power at all.

Half of the interior fuse box is always powered as it has a direct link to the battery through the main fuse. The other half becomes powered with key on. Yours is not good, as when you turn the key on something in the circuit is not operating properly.

The very first thing you need to do is get out the voltmeter and check for 12V at the 7.5A AM1 Fuse. Put one lead of the volt meter to ground, the other lead to one side of the fuse. Then do the exact same thing but checking the other leg or side of the fuse. You should have 12V on both sides of the fuse at all times.

You can also check for continuity across both legs of the fuse without evening removing the fuse from the box. If you have no continuity (no beep), the fuse is bad

Study the diagram carefully, make sure you are on the right one. Pull the fuse out, inspect it, replace it.

 

I have replaced this even though it was good just to be sure and checked it for 12 volts and am getting that there. This happened before and changing that fuse fixed my issue about a year ago. Now I'm stuck. Do either of you know what that DD connector is? Googling that I can't really find anything or where to look for it

 

Give me a minute... we will go to step 2

Step 1 was being absolutely sure that fuse was good.

 

I've been looking through the pinout diagrams and don't see a pin 62

 

Well I actually just now found this connector but have no idea where in the truck it is lol

 

Focus on connector DD, its a large rectangular connector coming out of the back of the fuse box. There are several of them so study it a little bit to make sure you are actually looking at DD and not one of the others. DD is the big one below the small 10 pin rectangle connector.

Pin #47 White - Power out of fuse box to ignition switch. This should have 12V+ if the AM1 fuse is good.
Pin #45 Beige - Power in to the fuse box when key is in ACC
Pin # 43 Light Green - Power into the fuse box when key is ON.

I would ground your volt meter lead, then use the other lead to check for voltages on these 3 wires.
When the key is moved forward you should start getting 12V to the Beige and Light Green wires. If you don't there is probably a break in the wiring inside the steering column to the ignition switch. Last one I saw like this the Light Green wire was pinched and broken in half.

FYI the Ground is Pin #62 on DD White/Black. You could check it for continuity to a good ground location also.

 

Is it one of these? I don't see it here, or do I have to fully remove the interior fuse box to get to this?

 

No its on the back side of those. There should be two coming out the back

 

gotcha yeah i cant get to those at all to test lol. I just stuck my phone camera back there to verify and yep they are, i have no clue how to take that fuse box apart, and i'd be risking damaging something else getting that thing apart.

 

I think it will just drop down off a mounting bracket. Those are the wires that need to be tested

 

Also you dont have to take it apart. Just use a paperclip or probe to test for voltage on a wire.

 

i gotcha, yeah i just cant get my hand back there to probe. I will attempt to unbolt these two bolts i see and see what i get from there. thank you so much for all your help man. i really do appreciate it

 

So I'm actually not getting any power to those 3 wires at the ignition switch. I am getting it to the lilac wire for ignition. Shouldnt it from there bridge those connections when the key is turned? Do you think the problem lies in the ignition switch?

 

so i'm actually not getting 12 volts to these 3 wires at the ignition switch, shouldnt that connection happen in the switch itself when the key is turned? also, do you think this would cause the alternator not to work also, because this all started with my alternator not working.

 

Again, I'm not a mechanic.
I don't want to steer you in the wrong direction.
Hopefully @Jeff_5_7 can maybe give you better advice.
He knows his stuff..

 

Check the White wire coming out of the fusebox and into the ignition switch (its should always have 12V+ as its directly connected back to the battery).

It supplies the power source to pass on down the line as the key comes on. Surprise Surprise the AM1 fuse is inline with that wire. IF the fuse is bad you will not get 12V into the ign switch.

 

At the ignition switch, the white wire on Pin #4 AM1 should have 12V all the time no matter what position the key is in.

If it doesn't look at the AM1 fuse or for a break in the white wire between the ignition switch and the DD connector in the back of the fuse box.

 

Ok just checked, I do not have 12 volts at the white wire, but I do at the am1 fuse. So I guess now is a scavenger hunt for a break which I've been looking at for two weeks now but have not found one.

 

Now would you recommend sending 12v to that white wire and seeing if my problem goes away?

 

Now I understand why these wires cross and connect.
It provides power TO the ignition switch.





Duh, I can't believe I missed that..

Thanks for helping him out..