ghost in the shell please help

Some electrical problem maybe? Please help diagnose.

When I turn on my left blinker and press the brakes at the same time, the blinker speeds up rapidly. But if I release the brake it blinks normally. When I turn on the hazards and check the exterior everything seems normal. And when I ask someone to watch the lights while I press the brakes, it of course performs normally not rapidly blinking...

To make this more weird... When I turn the truck off the AC stays on. But if I release the brakes or open the door the AC shuts off. Normally, the AC would just turn off when the key is turned off.

So I'm guessing there's a loose wire somewhere? But how would one track this issue? The breakers interfering with the blinkers, I guess I can wrap my head around, but the AC staying on when the truck is off? I'm pretty confused...

 

Maybe one of the filaments on a bulb is burned out. Did you replace bulbs with LED's or anything? Fast blink typically means it detects odd voltage and thinks a light is burned out. I'd start cheap with bulbs and go from there. LED's can trick the system. As far as the other problems, I'd not assume they are related until ruling out simple things.

 

Whole vehicle is stock including bulbs. They all appear to be working just fine.

 

The only thing I've done is plug in a dashcam... The truck has two 12v cigarette style plug-ins... Maybe the dashcam draws so much power that it's confusing the system?

 

A dashcam shouldn't draw much power. While the lights may appear to be working, refreshing at least the brake bulbs is a cheap way to rule that out. But you do have some other weird symptoms.

 

Maybe some mice chewed some wires under the fuse box?

 

Filament could be thinning out and not broken causing the trip.

 

Sounds like a bad ground causing current to backfeed other circuits.

 

Ground to battery? That I know how to check. Or ground somewhere random in the wiring spaghetti? IDK about that.

My go to mechanic says it might take a couple days to diagnose with all the other work he has lined up specifically because the AC staying on while the brake pedal depressed... But just like everyone else, I ain't got time for that gotta get back to work...

 

That part is odd but not it could be a wired grounding out and bad ground. Not the main harness but somewhere in the loom. Sorry OP

 

Burned out brake light?

 

Replace the brake light bulbs and i bet your problem will be solved.

 

Could it really be that simple? Seems like the most popular response. I just can't fathom why the brakes make the AC stays on... Guess it's worth a shot.

 

I mean main grounds to the engine, body, and frame would be the first thing I'd want to look at, you may also want to check your bulbs as other have said but I highly doubt that a bad buld would affect your AC.

Did this all start happening at the same time?

When you say your AC stays on I'm assuming you mean your blower? Or do the panel lights stay on as well?
Any other oddities that you have noticed?

 

I'll have to be more diligent to answer that about the panel lights. My gf spared a few minutes before going to work and we took 'er out this morning and everything seems to be working fine. Hit a couple speed bumps to jolt the vehicle thinking it's a loose wire somewhere. But everything is working normally.

Similarly, yesterday I stopped in a random parking lot and asked a stranger to look at my lights and everything worked just fine so he probably thought I was crazy.

Yes this all started the same day two days ago. The first day I thought it was just a bulb, but then yesterday I noticed that both the rapid blinking and AC thing wasn't random, it's definitely related to the brake pedal somehow...

 

Here's a post that shows some of the grounding locations (for a 3rd gen, but pretty sure 2nd gen is the same). https://www.tacomaworld.com/threads/grounding-locations.724741/

I think it's a good idea to check all of those ground points. Still, I would replace the bulbs regardless of what some dude in a parking lot said.

 

Electrical issues can be difficult especially if you aren't well versed in electrical theory and operation, being intermittent on top of it makes it really a challenge to find.
I've glanced over the diagrams and I can't really see anything the blower and brake lights have in common.
Have you ever had any water leaks in the cab that you know of? Corrosion in a connector or junction box would be another variable.

All the relevant diagrams I can think of are attached below.

 

Have you tried replacing the brake light fuse? Perhaps fuse has a microcrack and is intermittently opening and shorting as it heats and cools. That could explain the strange blinking behavior.

For the AC or blower, if there is an equivalent relay on another circuit try swapping that out and see if the behavior follows the suspected relay.

 

This could be an indication one of the bulbs isn't working.

Like dm93 said, possibly a bad ground somewhere. I had a car with a bad ground to a front light assembly. It would do all kinds of things. Not flash, work perfectly fine, flash one bulb but not the other.

You could try running a long jumper wire from battery ground then touch the other end to the light grounds, like touch it to the metal part that's obviously grounded, see if anything changes.

Intermittent issues are a pain. You can't troubleshoot it while it's working good, and it'll be working good when you're trying to find the problem. You almost gotta get lucky to catch it at the right time.

 

Ghost in the CAN Bus