Data Hacking

Chapter 2 — Building GPS Data Cables and Power Cords
4. Using a multimeter, you need to determine which wires corresponds to the data in and
data out and ground pin on the 9-pin connector, as shown in Figure 2-7. To do this, set
the multimeter to “ohms” (the 20 ohms setting will do just fine). Attach one probe to the
bare wire; wrap a length of paper clip around the other probe, and probe the holes in the
connector. Try them in turn; you are looking for a reading of zero, indicating that you
have the right wire for the pin. The pins are as follows:
■ Pin 2: Data out
■ Pin 3: Data in
■ Pin 5: Ground
FIGURE 2-7: A multimeter makes it easy to trace what wire goes to which pin.
Carefully note which wires correspond to each pin. If each is colored, make a note
of this.
5. Trim back all the unneeded wires and cut the wires from pins 2, 3, and 5 to a length of
approximately 1 inch (25 mm). Trim the sheath from these wires back about 1 ⁄4 of an
inch (6 mm), as shown in Figure 2-8.
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