I am in the process of installing new Cyberdyne digital gauges. However, they are super bright. I wired them correctly tapping into the cigarette lighter. Anyway, I figured out that I can have them on the dim setting from the get go by wiring the dimmer wire to the power source rather than the dash lights (grey/red wire). They gauges are at the "night time" dimness all the time. However, they are still to bright. Could I install a resistor on the dimmer wire to dim the gauge more? The logic circuit and senders would still get power from the red power wire. It is my theory, since the gauge is sealed, that the dimmer wire over-rides the red power line for the LCDs only; the logic circuit and senders still receive full power. Any electrical engineers out there?

 

there's only one way to tell... Try it! But, it depends on how the circuit is driven. If the LEDs are driven by that wire, it would work. If the LEDs are controlled by a voltage on that wire (nice, because the load is much lower, with all the power coming from the main power line), then it won't work, and you'll need two resistors to make a voltage divider to set the brightness. If this is the case, you can use a potentiometer and have it adjustable!

Matt

 

You might have to pad the dimming circuit with a resistor or pot to get it in the range you desire. Problem is, the dash lights are dimmed using a PWM circuit that changed the duty cycle of a 12 volt source (switches it on and off at about a 200Hz rate) rather than linearly adjusting the voltage level. This can make some gauge (or radio headunit) illumination either go crazy or not dim at a predictable rate. In some cases, a resistor and diode in series with the dimmer lead and a capacitor (about 50uF) across the gauge dimmer input will approximate a linear dimming control at the gauge. Select the resistor value depending on the illumination level you desire, the easiest way to do this us use a pot/rheostat in series, adjust it to your liking, and use the derived value to select a fixed resistor. Or, just hide the pot somewhere for future adjustability.