My transmission temperature gauge is too bright at night and blinds me a tad, even though its hooked up to my dimmer switch. I just bought a toggle switch to cut power to the gauges light source. Where is a good place to splice it in? I was thinking put it in the line that runs from the dimmer to the gauge.

 

You can put in a resitor on the power supply line that would dim the light.

 

You can also give it a light mist of high temp paint to "dim" it out. Thats if you can get to it to do so.

 

Depending on what the current draw is for the light part of the gauge this would be the best way to reduce the power being supplied to the light circuit. Just make sure you get a high enough wattage resistor to handle the power dissipation. You will have to play with the resistance value to achieve the brightness you find comfortable. I would suggest getting a variety pack of 1/2 watt to 1 watt resistors to be safe and try them in series with the 12v power wire going to the light part of the gauge.