DRL mirror switchbacks killed my truck

Since you have removed and replaced the fuses and still no juice, I guesstimate something bigger has failed. The dimming of the dash lights (which is tied to parking light circuit) is handled by the head unit. The relay is ON or OFF. Power to TAIL and Panel fuses.

 

Ok... I understand the words, but not really following I don't think... So you're saying the head unit relay could have tripped?

 

Caribe, you're gonna have to break this down like Barney style for me man

 

The Main Body ECU - which is attached to a junction block filled with relays and connector headers - is a computer board that handles lots of things. There's no trip reset for the Parking/Panel circuit.
For the Parking/Panel circuit it's a plain-Jane one, an external switch (steering light stalk) connected to the Main Body ECU provides a ground to that relay via the ECU.

So looking at the drawing you have a 120 amp fuse which ties into the Junction Block, then to other relays and circuits. Terminal 1 on connector 1K provides power to TAILLIGHT circuit (pins 30 & 86), this relay is soldered to the junction block. The relay provides power to the panel lights and the tail lights at same time. The Panel lights have a tie into the Head Unit for dimming.
Looking closer you'll see that the ground on the relay coil side (85) ties into pin 14 of the Main Body ECU. From the MBECU, connector M6 pin 22 ties into the steering wheel light stalk (Light Control Switch), where ON/OFF is selected for this circuit (among others)

 

The picture shows the junction block with the Main Body ECU removed...

 

This is the Main Body ECU - front n back -

 

Thanks for all the information man.

How do I get to the MBECU from the fuse box?

 

I'm assuming that the 5 Amp fuse in the above drawing (@ Pin 55) is for the Dash Lighting? @JordanJake25 Does the dash lights still function?

So it appears that the Junction Block is attached to the MBECU with header pins (and can be separated). If we can confirm that the Dash Lights are INOP, I would be tempted to replace the entire Junction Block assembly.

Why did Toyo have to make this so difficult?

 

89221 is the MBECU...it's attached to the Junction Box.

What do you plan to do?

 

Hey OP is that ORANGE wire the TAILLIGHT wire? Is that connector still attached to the ORANGE wire?

If the answer is YES then REMOVE that connector, cut the ORANGE wire in half and get slack then reconnect the ORANGE wire. See if your brake lights work again.

 

Looks like the Junction Block is ~$200. Still cheaper than the Dealer (if we can make a better educated guess). Exact PN's can be verified after removing the original part.

https://www.toyotapartsdeal.com/par...(1=2GRFKS;4=SR5;6=6FC;7=DCB;0=GRN305L-PRTSHA)

 

OP-- do not remove/or work without first removing the negative terminal from the battery and waiting a few minutes...

https://www.tacomaworld.com/threads/psa_fyi-ground-terminal-from-battery.628383/

 

No OP. You're gonna need to ASK Caribe to break it down for you instead of you demanding he break it down.

 

Ok guys I'm gonna try to respond to all y'all, but thanks so much for the input and suggestions.

First off, I'll attach a pic real quick and try and explain what I just did. So above the fuse panel there's two relays on the side of the junction box. I assumed one would be responsible for tail lights, so I tested them both. Both had a green light. When I went to put the bottom one back in (they are both identical 12v) I could audibly hear a click and the 3rd brake light was turning on and off as i made the connection. Tried swapping them and turned the truck on and no luck. Which leads me to believe that caribe is right, and the problem is deeper. Whether it's the MBECU I have no idea, and his knowledge is obviously way more extensive then mine will ever be.
@MikeyD.25 yes the connector is still on that orange wire, and as far as I know that orange wire powers the DRL'S. I just followed the manufacturer instructions on that one. But I can try getting those off and reconnecting, problem is there is almost no play in those wires at all, but I've got other 18g wire I could splice onto.
@phoenixford yes the dash lights still function, everything functions normal, aside from tail lights and the white LED function of the mirror lights.
I've also checked every fuse and relay in both fuse boxes and can't find anything wrong, so again I'm worried that caribe is right. That being said, I'm in WAY over my head here... If I purchase a new junction block, will that just plug right in or am I gonna have to like solder connections and shit?

 

Well this trashes my theory on the relay assuming that I'm reading @caribe makaira drawing correctly.

Here is my last (guess) - Remove the T-Tap. Strip back some of the insulation around where the t-tap was connected to inspect the wire. Make sure the wire isn't broken.

 

Well shit. Yes that was disappointing. @PhenixFord what's the t-tap wire?
@caribe makaira thanks for all the help man, couldn't have made have of this troubleshooting without ya. In your opinion, do you think a new junction box is the solution, or pull the existing one and troubleshoot the solder connections based off of the other pics you sent before?

 

Roger.