(MOD) Hazard switch & Passenger airbag/belt indicator LED color.

I intend on swapping out the Orange airbag LED's with Red LED's because I want them all to be red. I recently spent some time this weekend reverse engineering the circuit used to power the dash hazard switch indicator & the passenger airbag-belt indicators.

You are responsible for whatever you do to your truck. This thread is for academic purposes only.

I made the full schematic of this module for the version without a clock. Before I start swapping LED's the last thing I want to do is take some voltage measurements on the board to get the max current through the LEDs & their drop voltage.

Here's the LED layout. LP1 is the incandescent bulb (Can't change the color of the hazard triangle). I'm thinking of swapping LED2, LED3, LED4 with RED LED's.


Here's the front of the circuit board & the LED positions. The hazard switch uses an old fashioned incandescent bulb, but everything else is an LED. If you look at the square silkscreen on the left side next to the switch you'll notice where the clock would be soldered in previous models.

If you're smart you don't play with circuit boards on a microfiber towel. I can get away with it b/c I'm good luck.


I found out they only make one version of this circuit board & the plastic enclosure for all Tacoma's. It looks like the only difference is that in this module they don't solder the components for the clock & the plexiglass on the front. You can see where the hole in the enclosure for the clock & buttons. My guess is they save about a dollar per module without the clock.

 

Here's the schematic for the module without the clock. I used the zener diode symbol for all of the diodes, but I doubt any of them are actually a zener diode. I will update this thread when I finish my voltage measurements & add a more detailed analysis of the circuit, it's inputs & the part number of possible replacement LED's.

LED Sizes:
3mm LED: LED1, LED2, LED3
5mm LED: LED4, LED5

Incandescent Bulb: (LP1, Hazard switch light).
21.4 Ω (Ohms)

Transistor: (TR4)
I believe the Transistor is the Toshiba 2SA1201-Y PNP. Actual dimensions (4.40mm x 2.40mm w/o measuring sink).

Connector: (HARNESS)
I just used the only symbol I could find that matched the circuit.

Hazard Switch: (S3)
I just used the only symbol I could find that matched the circuit.


Here's the value of all the resistors: (All values in Ohms)

Small Resistors (1.6mm x 0.88mm): R6, R15, R20.
Medium Resistors (2.11mm x 1.30mm): R8, R9, R11, R17, R22
Large Resistors (3.16mm x 1.55mm): The rest of them.

There are two types of diodes: Name - (Marking).
Large Diode (2.60mm x 1.59mm): 24 (marking)
Smaller Diode (1.77mm x 1.31mm): C1 (marking)

 

Here's the wiring pinout on the Hazard display module. I took the image from this thread and edited it to make it more correct & relevant to my thread.
https://www.tacomaworld.com/threads/adding-dash-clock-to-15-tacoma.403452/

I used the same symbols/names as the schematic & my first post. The orientation of the connector in this image is the same as the orientation of the connector in the schematic.

The LED Dimmer doesn't work on LED5 (Passenger seat belt indicator). Something I learned from the schematic & confirmed in my pickup.

 

Since your going to all of this trouble, why not design the circuit with rgb leds. You could use negative provided to turn it on as usual and then pin 3 to provide voltage for controller for color management. Might have to actually have pin 3 power the controller for the color control. It would then be possible to actually RGB accent the interior. If that is your thing. I think it would be cool for fun factor. Probably not useful. But many thing we do to vehicles may arguably be "useful". It could be considered useful to be able to use the white color to see extremely well in the truck, while the other colors might just be cool.

Of course being the board is what it is, you would have to hand wire the power leads for the RGB Led which would mean only the ground would be holding it in the board. Which may not even be an issue. You could also possibly use pin 1, 2 and 4 to power the leds color leads. Depending on where pin 3 power comes from ( I know! from the battery, haha, I mean wherever the other end of this harness is) you could disconnect that source(since you are good at removing pins you could pull the wire and maybe put a new pin in, to keep the factory wire still there insulated of course) use that for one of the color leads and use the existing pin 3 trace for one particular color, have 2 led leads/pins in the board and doing this would enable you to put the controller through the harness, which would enable you to place the controller at the end of the harness and use it to control other RGB madness you decide to install. (this also would mean you would only have to and solder 2 wires to the other 2 led leads for color) Heck there might even be some function through the head unit and maestro to control this being many newer vehicles have interior color lighting control. Now I am not sure what controls the colors in these newer vehicles, but it is accessed through the radio or display interface.

Anyway I kinda went off on a deep tangent with your idea here and took it to a nerdy computer level RGB scheming level. I hope some of it made sense. But the lighting in our 2cd gen isn't exactly to be desired although it's not the worst by any means. With all the cool audio stuff you have going on.... why not?

 

It would be super cool, but it's a lot more work than just swapping the leds out with a similarly spec'd one of a different color.