To be able to interact with our ECU you need to connect a computer or handheld device/PDA to the OBDII diagnostics port on your car. Described here are the authors notes on how this hardware interface can be set-up.
What do you I need?
Software is loaded on the computer which ‘talks’ to the ECU via a cable connecting it to the OBDII connector. The author used the reasonably priced OpenPort 1.2 ODBII cable from Tactrix in the USA for $79 (£45). This cable is compatible with various Subaru ECU diagnostics, reading, editing and reflashing OpenSource software described on this site.
Below are details of how to connect is all up for data logging/monitoring and for reading/reflashing your ECU.
Data logging/monitoring connections
The Tactrix OBDII cable has a USB connector on one end and an OBDII connector on the other - but that’s not all. These cables include some basic electronics to convert this interface for use with, and to electronically protect, the computer to which it connects.
To get it working properly, you must first install EcuFlash
When EcuFlash is installed, the drivers for the Tactrix cable are installed as well. Once EcuFlash is done installing, plug your Tactrix cable into your USB port. Say “No, not this time” at the first dialog box. At the next dialog box say you want Windows to search for you (reccomended). At this point the cable should install. Once it is installed you are ready to begin using the software of your choice. Connect the other end of the Tactrix cable to your diagnostics port. [Added by: 02BlueSuperRoo from NASIOC.Com 05/15/07]
The author simply connected it to the OBDII diagnostics connector under the steering column of his MY03 WRX, and tested it using the ECU diagnostics software called ecuExplorer, and it all worked first time.
Note: When simply data logging using EcuExplorer you do not need to connect any other connectors under the dash
Reading/reflashing ECU connections
If you are reading and reflashing ECUs you also need to make other connections. With your ignition turned off, and with reference to the following diagram, you should connect the green ‘test’ mode connectors found under the steering column.
Figure 1 - MY03 Impreza 2.0 WRX (EURO)
For all Drive-By-Wire (DBW) Impreza models that is all you need do. For all other Subaru’s, you need to jumper the flash block connector illustrated above. You have two options to ‘jumper’ the flash block connector, either by purchasing a flash block connector or simply using two wires to short the relevant pins.
There are different styles of flash block connector. Below illustrates two connectors the professionals use to jumper the flash block connector. Note that these connectors fit on to ones under the dash so they are the male side of the connector - you’ll see the female side under your dash. Investigations via the OpenECU.org community show that the connectors below are from Sumitomo Wiring Systems part number 6090–1149. Unfortunately they only sell in bags of 100 so a group buy would be a good idea. Also Subaru sells a Jumper Harness Kit for ECU/TCM reprogramming. It is part #24036AA010. It’s pricey, $28.98 from this US web site and £44.23 + VAT from a local UK Subaru delear. Also please find attached a document which shows which jumper harness kit to use for recent US Subaru models. A final update: Tactrix now sell the flash block connectors for New Age cars at around $9.
|Figure 2 - Flash Block Connectors for MY 2002 - 2005 Impreza|
If you don’t have the above connector then short the wires yourself. If you have the 2002-type connector join both pins together. You can do this my stripping and tinning both ends of a wire and inserting it in to the connector. If you have the 2003–2004 type connector join pin (1) to (2) and pin (3) to (4) on the white flash block connector shown in Figure 1.
What software is available?
Various software is available, both OpenSource and commercial. This site will concentrate on the OpenSource software available described within the related articles below: