Instrument Light Take-off

I am wanting to connect aftermarket illuminated switches to light and/or dim with the instrument/radio/dash lights. Where do I find this wire? What color is the wire?

 

See the image below:

The power wire Green is attached to the illumination bulb and the ground wire green with a white stripe is attached through the dimmer to ground. The dimmer rheostat controls brightness using the ground.



So in answering your questions:

Power 12 VDC is the Solid Green Wire.
Ground is the Green Wire with a White Stripe.

 

I picked mine up from the illumination wires going to the HVAC controls, it was easy to pop out and plenty of slack.

Keep in mind that this is a PWM control, not a basic rheostat.

As mentioned you have to tap into both wires from the control. I used two fuseholders and put a fuse in each of the wires feeding the gauges (one fuse in green, one in green with white stripe). One wire will always be 12V to the body of the truck, the other wire will vary between a few volts to 12V to the body of the truck. If you have it dimmed pretty far, both wires will be close to 12V when measured from the wire to the body. A fault in either wire would cause issues. I have mine fused at 1 or 2 amps I believe.

Incandescent bulbs typically won't work very well because they dim at a different rate than LED's. Since the truck has LED's you'll also need to use LED's to get the right rate. Otherwise a typical incandescent would barely be on and the dash lights would nearly be fully bright.

Another issue from the PWM control means that you must use a gauge with an entirely separate lighting circuit. Many aftermarket gauges have a ground that is shared by both the gauge internals and the light. Since ground varies and is pulse width modulated, the gauge won't work properly and could be damaged.

I added Autometer gauges from their custom shop that were closely matched to the factory gauges. They actually look better since they use real carbon fiber. If you want what I got, let me know and I'll dig up gauge info and can get the custom shop order info. Autometer techs can help you find a gauge with an entirely separate lighting circuit.

Before buying I talked with Autometer to confirm that the lighting circuit was entirely separate as a lot of Autometer gauges have the shared ground mentioned above.

Then I tried the incandescent bulbs provided just to see what happened and the dimming profile between the incandescent bulbs and LED's was unacceptable. The factory LED's would nearly be blinding and the incandescent bulbs were barely on.

So then I bought some LED's. The dimming profile matched but the LED's were a little too bright and the wrong color. I spent about $10 and tried an LED set with a lower lumen output but ended up going too warm on the light color. Finally another $10 later I got it right and used lower lumen LED's with a slightly cooler color.

The too bright lights were Diode Dynamics HP5 6000k
The best match brightness but too warm were Diode Dynamics HP3 4000k

The best match were Diode Dynamics HP3 5000k, this very closely matches the intensity and warmth of the factory gauge cluster.





Crap---- I didn't pay close attention, you're wiring up switches! Same thing, you've gotta find switches with lighting that is LED and entirely separate from the rest of the switch contacts. I have a push button switch to turn off my ABS but didn't use the light inside because it is an LED but shares wiring from one of the contacts. I can make the light work but it wasn't dimmable because I couldn't connect to the lighting circuit and it was too bright for me.

 

Green with Red runner on a 2002 for illumination (+)
White with Green runner for Illumination (-)

 

Good catch. I didn't notice he was a 2002 in his sig...

 

Yeah, but maybe he's working on an 2nd Gen...