Recently bought an 84 c10 as a project. The four small gauges on the left are not typical gauges I’ve seen but have a light behind them.

Im looking to replace them with new gauges but I’m unsure how is the light gauge triggered? Do I replace them with a new sensor like I would for digital gauges? How does the light gauge work?

  • 1
    Not sure what you mean by "light gauge"? Wiring is fairly simple on these trucks. Feb 4 at 15:01
  • These are light driven if that makes sense. Like not actually a needle just a bulb behind the screen that comes on some how Feb 4 at 18:44
  • 2
    These are what most of us would call "idiot lights". Feb 4 at 19:34

1 Answer 1


The way the current lights work is, the sensors read what the temperature or oil pressure is and when what it is sensing gets out of whack (too much temp in the coolant or not enough pressure in the oil), it grounds and causes the circuit to turn the light on. It really doesn't sense the amount of pressure or temperature, but rather, it has a point for where when there isn't enough oil pressure to keep the sensor from grounding, it grounds and turns the light on. The temperature sensor doesn't ground until the temperature gets too high. These are the epitome of a "dumb" sensor.

To put new sweep gauges (ones with needles showing you the actual reading) or even digital gauges, you'll need to replace the sensors which are located in the engine and wire them back to the new gauges. You might be able to use the current wiring, but some of them may require to wires coming off of the sensor for it to work.

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