On Board Air brand Toyota Switch won't dim

I bought one of the On Board Air Toyota look a like switches (looks like a Tacoma fog light switch) to install in my 2013 Double Cab. The switch installed properly and works well. The back light comes on and off with the dash lights, but does not dim.

I have previously wired in the Toyota Highlander heated mirror upgrade from the forum here without difficulty, but this has me stumped. The OBA switch only has four wires: power in, out to the relay, ground, and a single wire for illumination which I wired to the green wire on a nearby factory switch.

Any ideas?

Thanks!

Geoff

 

I think the actual LED has to be a dimmable one.

 

If it's like the fog light switch it goes

Pos+
Neg-
Illumination
Illumination

Did you tap both illumination wires to both green illumination power wires from another switch?

 

Jerez:

The pin out from the vendors wiring diagram is:

1. +12 volt power in,
2. relay pin 86
3. ground,
4. dash light or +12 volt

I wired Pin 1 to ignition power, Pin 2 to the device, pin 3 to ground, and pin 4 to the solid green wire on a nearby switch. The back light comes on and off with dash lighting, but won't dim.

The attached lights turn on and off as expected however the back light won't dim. Large may be correct, and the LED may not be dimmable.

 

That's weird...any led I've added to switches have all dimmed perfectly
Post a picture of the switch!

 

The dimmer in second gen tacoma works in reverse. The stock dash lights are grounded through the dimmer circuit that varies that ground voltage from 0V (full bright) to 12V (full dim).

So, you can make your switch dim by grounding the switch to green/white instead of ground.

However! Many after market switch bodies ground the switch and the switch LED through a common ground. This means that it is possible to backfeed current from the dimmer circuit through the switch to unknown and probably bad effect.

So, If your switch has a separate illumination ground, ground it to green/white and it should work OK. If not, you'll have to build or acquire a voltage comparator to drive the LED with the difference of the light circuit (12V) and the dimmer circuit (0-12V) which will result in the light dimming (approximately) with the dash lights.

This thread has some more info.

 

I was afraid of that...

I am okay with the inability to dim the backlight based on the fact that the breadboard circuit is not something I want to build right now.

Thanks for the assistance however

 

O.O