Well my buddy has a 02 screw XLT and he's putting in a system. Im looking into trying to find a way to convert the thermometer in the overhead console into a volt gauge. I dont know if its possile but I think it would be sick if it can be done. I got a couple ideas Im gonna try this weekend.

 

why lol

 

x2. What he said^^^! Why would you want to do that????

 

cool idea, though an A-pillar pod and digital guage is alot simpler.

 

its darn near impossible unless you are taking one out and putting in another. Or you know more abt circuitry than earthly possible... Have fun...

 

Probably not too hard...although it is not going to be "plug and play." You would need at least a rudamentary backround in electronic design, or have a friend who does.

What is physically located in the mirror is just a dual digit 7-segment display. The actual temp sensor is elsewhere. You would need to do some research and find out exactly what type of driver IC is needed to send info to the display...probably just a plain jane 7-segment display decoder driver. These can be found at Radio Shack for a couple bucks. Then you could just feed the decoder driver IC what ever you wanted displayed on the mirror...that sounds alot simpler than it is...

Something that might be easier...providing you can find this stuff, would be to buy a voltage gauge that has it's sensor remotely mounted from it's display. If you can find one that has a similar dual digit 7-segment display you might be able to just cut the wires off the volt meter and hook them up to the wires leading to the mirror's display...you will need a wiring diagram for the mirror and the volt meter you buy since you would be gutting both.

I think the biggest hurdle you will have to deal with is that the mirror display is limited to two digits. Most volt meters are going to output at least 3 digits, i.e. 14.2, 13.8, 10.4, etc... With the mirror display the best you could do is 14, 12, 10, 11, etc... You will need to find a volt meter that only outputs two digits, or build a circuit, or program a microcontroller, or...,or..., etc... that will round off the volt meter's output and provide only 2 digits to be sent to the mirror.

Hope this helps, good luck with your project.

Mike

 

tell him to quit being a cheap a$$ and buy a radio with one on there


AKA my pioneer

 

I gave this a little more thought and realized you might even have it easier than I originally thought. Of course, this depends on the design of the mirror...which I do not have access to. However, here is my other thought.

In my last post I talked about a 7-segment display decoder driver IC. What I realized after the post was simply that the display driver is probably already located in the mirror, along with an analog to digital (a/d) converter and microcontroller that probably, again, I am guessing here, probably just reading a thermistor located elsewhere in the truck. A thermistor is a resistor that changes value (ohms get bigger or smaller) depending on the temperature. This is how most electronic temp sensors work. A lookup table is programmed in to a microcontroller that provides a correlation between a given resistance value and temperature at the thermistor. What really happens is an a/d reads the voltage drop across the thermistor and feeds this info to the micro, which then spits out the temperature data to the display.

Now, how does this help you? Well, if my guess is correct, all that causes the display to move its digits up and down is a change in voltage seen at the end of its wires. So, you could take a power supply and experiment to see what voltage at those wires cause a given number to appear on the mirror. Then you would need to look at the output of your volt meter and see what voltage it outputs for a given reading...it should be scaled somehow, like measureing 12 volts should have a given output from the sensor, like 1 volt...or some other value. The actual value doesn't matter, but it should scale linearily with the volt meters measurement, so if 12volts at the sensor equaled a 1 volt output, then 6 volts at the sensor should equal 0.5 volt, or 24 volts at the sensor should be 2 volts at the output...get my drift?

Once you know what the scale of your volt meter's output is, compare this to the scale you find out with a power supply and the mirror. You would then need to get the scales to "match up." In other words, if 12 volts equals 1 volt out of the volt meter sensor, the 1 volt in the mirror wires needs to display 12 on the mirror display. This might be a little tricky, but since it too will be a linear scale, you should be able to get away with putting to together resistor divider to get the appropriate voltage to the mirror to display the voltage.

Again, I have made some pretty big assumptions here. The best thing you could do is get a wiring diagram for the mirror. I would also consider getting used mirror for the junk yard to experiment on before doing trial and error on the truck.

Later,
Mike