I2C Digital gauge indicator logic level shift

[system]

• Why are you connecting SDA and SCL to pins 2 and 4? --->> I tried to connect to SDA and SCL, but in the code Im using CLOCK is connected to interrupt on pin 2, and digital pin 4 for data.
• Why are you not supplying power to the device? --->> The device is using 1.5V battery.
• Why are you using a LM339? That's a "Low-power quad voltage comparator", not an I2C level shifter. --->> Im never did level shifting
• Why are you not connecting Gnd from the gauge to the LM339? --->> Where should I connect GND?, I tried to GND on Arduino??
• What is the part number of the "Digital Dial Indicator Gauge"? --->> http://www.ebay.com/itm/DIGITAL-DIAL-INDICATOR-GAUGE-25-4MM-1-LONG-TRAVEL-MEASURING-SETUP-TOOL-H16-/150795623876?pt=LH_DefaultDomain_0&hash=item231c1e9dc4#ht_3924wt_1163
• What is your code? Thats the code --->> http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1288396532
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