For a group of modern day gear heads I am disappointed in all of you.
I am providing the the following for all of those who own a 92-95 Honda. More specifically I am providing the following so you can interface. to your vehicles and write some good software (Hint for the programmers)
Pop open your ECU normally located under the carpet on the left passenger's side kick panel (you know between the door and your feet) typically for USDM and Canadian manufactured Honda vehicles. Assuming you know what you are doing carefully remove the ECU (make sure the car is off and Battery is disconnected) Take the top Lid off (this is the one with the 5 screws on top and no ridges) Locate an area screened in white "CN2" This is a 5 Volt TTL port and the pin outs are as follow reading from left to right.... meaning from the vehicle's connectors to the EPROM 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 uses half-duplex (RX and TX are connected and also Gnd) Note this is the stock configuration.
You can convert your ECU to a Full Duplex system however you will no longer be able to use the diag harness located under your dash if you do this.
PGMFI Notes: J12, when removed, disconnects the receive line from the transmit line, so the serial port can work in full-duplex mode, meaning both devices can send to one another simultaneously through CN2. This, of course, breaks the stock diagnostic connector under the dash. However, the benefit of full-duplex mode is more reliable Data Logging. Some programming work is in progress to take advantage of this to log data at a much higher sample rate without clobbering any commands sent to the ECU.
On a JDM P30 (Small Sqaure) ECU it is the J4.
Now for the disclaimer: Please note information and serves for educational purposes only I am not responsible for any damages or if you mess up your own ECU.
In addition you can use a TTL to USB or a TTL to RS232 Serial Cable to Pick up the Signals and then translate within the software.
remember don't confuse TTL for RS232 although these both have RX and TX signals. also remember there are 5volt TTL and 3Volt TTL systems.
And finally I am just kindly saying I am disappointed. In actuality I am very proud of my community. If were not for people like all of us in here Hobbiest, Techno Junkies, etc... Bill and Ford would of never taken interest and copied what our community has done.
Sincerely,
D.Esco
of MobileEmpire.org