Cargo light flickering

I have a 2017 tacoma off road double cab and tonight my wife noticed that my cab/cargo lights are dim and flickering when my lights are on, but when I open my door or turn the switch on they are as bright as ever. What could be causing this?

 

Any other electrical mods?
Look first, where the human was last

 

No electrical mods and this is the stock led brake/cargo

 

I believe the Cargo lights have constant positive and ground through the switch. So flickering would be conducive of the ground wire actually grounding on a body panel (or bolt) between the light and switch. You may have the wire routed against something that rubbed through it slowly. It’s very easy to test that if you can gain access to the bulb. But on the cargo light, that’s a total bitch, if you’re still under warranty, I’d let the dealer see if they can fix it. If not, you’ll probably be in for a ton of hassle pulling interior panels and maybe headliner. So first off, as mentioned above, is your wiring stock?

 

All wiring is stock. But the other day I had the dealership take loose a “noise maker” behind my back seat by the seat belt, they told me it wouldn’t impact anything but I wonder if the two are connected some how

 

I believe the wiring runs along the floor / door cill into the back, then up behind the rear seatbelt on the drivers side. (I’m not 100% sure though). If it does , then it would make prefect sense that they punched the wiring when they put the panels back together.

 

Well there ya go

 

No...the Cargo Light Relay has constant positive...the switch provides ground to relay, this goes into the Main Body ECU (if switch is DOOR or ON) if switch is on DOOR then Main Body ECU provides path to ground via purple wire (closing relay coil = light ON); if switch is ON, then switch provides ground via another wire (red)
This is a simplified view of circuit, there are other components to it. (door sw's, unlock detection sw's, door lock control receiver)
route of Cargo Light green wire

OP, this dimming and flickering is always while vehicle is ON? Cargo Light stays this way as you drive?

 

Are you sure the green wire is the cargo light? Seems like the next wire over is since it is probably connected to the cab lights in some way, you can make the cab lights/cargo light come on with doors opening closing by switch position. Just a thought.

 

I'm assuming the blue describes your headlight switch; red and green describe the cargo light switch.
If so, my thought is the blue wire in the wiring diagram is grounding out, poorly; causing the cargo relay's coil to 'chatter'. The cargo is not supposed to be on with the headlight switch alone.
When the relay receives a clean ground from the ECM/cargo switch, it works like it should.

 

Yes the cargo light stays dim and flickering while driving. It does it weather the headlight switch is on or off

 

I don’t have the dealership option for flashing third brake light

 

I'd pull the relay and check resistance to ground on the socket for pin 2.

 

No..the blue is the ground wire coming from the relay to the Cargo Switch.

 

Yes..it's the green to the Cargo Light

 

Blue refers to what I highlighted in OP's post.

 

Remove the Cargo relay and the Mirror Heater Relay. Place Mirror Heater relay in Cargo spot. Verify.

 

There's no relation between the headlight switch and the cargo switch except the vehicle power source and ground.

 

I know...I say as much; "The cargo is not supposed to be on with the headlight switch alone."
I will concede, the word "alone" should have been "at all"