Frequently Asked Question

CN2 is the connector to the serial port on an OBD1 ECU.

Here's the pinout of the Data connector IN a Honda ECU:

1: GND

2: RX (send Data from the PC to the ECU)

3: +5 Volt

4: TX (send Data from ECU to the PC)

5: N.C. (not connected)

This port is half-duplex (RX and TX are connected) in stock form. See OBD1 J12 for more information about full-duplex modification.

A good pin header for CN2 is Digikey part# 640456-4

Question From Web Geek_ "There are 3 search results for that part #, which is the right one?"

For more information see this excellent post by Jim Truett: http://forum.pgmfi.org/viewtopic.php?t=1663