Select monitor and `90s SUBARU cars page
For those who love 90's SUBARU cars
Select Monitor(WRX) | Select Monitor(SVX) | Cruise Control
Reproducing the functions of the SUBARU Select Monitor on a Windows PC

When my car has a problem and I take it to the dealer, the mechanic connects a machine and checks it. That's the Subaru Select Monitor. This device has been updated several over the years, and it seems that the type called SSM2 was compatible with Subaru vehicles until about 1998, before OBD II became available. As the car gets older, parts here and there start to wear out. Until the 1980s, cars had carburettors, which can be maintained only by mechanical disassembly, but since they changed to electronic fuel injection using a microprocessor, the car becomes useless when the ECU or sensors deteriorate or become damaged even if the mechanical parts in working order. In Japan now, it is no longer possible to pass the vehicle inspection if a warning indicator such as a check engine light.

This is a big problem for the '90s cars. You usually need diagnostic equipment such as a select monitor since sensor degradation cannot be seen just by looking at it. It is difficult for users to obtain this because it is not sold to the general public though SUBARU dealers and only auto repair shops can buy it. However, there seems to be someone in the UK who analysed this select monitor. Please refer to "Diagnostics and Datalogging for Subaru SVX" website with click here. My software was basically designed from the information in there. Many thanks to Phil Skuse for the information. There was no information about Impreza WRX on his page. Then, I created a ROM analize tool and checked where various parameters were located. There was a M37700 bdisassambler before, but this tool can be analyzed a little more detail. I will explain this tool in another page later. In 2023, the Subaru dealer mainly uses SSM3 and SSM4, which are ODB II. The support of SSM and SSM2 for 90's cars seem to have expired, and they are not used now, and these old cars which has no ODB II ports may become impossible to diagnose in near future.

Currently, I am working to support the GC8/GF8 Impreza first and medium generation models (~ `98/September). I think it will probably be possible to support SF5 Forester. Since the first model has several differnet information, the beta version displays double information. As soon as I found which parameter is correct, I will delete wrong one.

What "Select Monitor for Windows (Impreza WRX edition)" can do are as follows

  • Read ROM ID of the ECU(Engine Control Unit) (Able to read ID's even your car is not SVX)
  • Read and clear the ECU trouble codes
  • Read of current values of internal parameter of ECU and real-time graph display (up to 4 items)
  • Display of fuel control and ignition timing map in the data read from ECU or downloaded ROM data
  • Read whole ROM/RAM data in the ECU
  • Read ROM ID of the TCU (Transmission Control Unit)
  • Read and clear the TCU trouble codes
  • Read of current values of internal parameter of TCU and real-time graph display (up to 4 items)
  • Read whole ROM/RAM data in the TCU

    Note1:The communication speed of the serial interface is slow at about 2000bps. Only a few parameters can be read out per second. Specifying many parameters slows down the display update.
    Note2:It takes several hours to read the ROM data. If you try to read it without starting the engine, the battery will definitely go flat. Take sufficient precautions, such as charging the battery with a charger.

    Example 1:Warm up

     As the water temperature rises, the ISC valve gradually closes and the idling speed slow down. Finally, it seems to settle down to about 800 rpm at about 70 degree.

    Example 2 : Knock correction

     It seems that the ignition timing is gradually advanced by knock correction when the throttle is not opened. Knocking detection returns the correction at once, and it seems that the correction is gradually applied again.

    Example 3 : Air/Fuel ratio correction

     When the voltage of the O2 sensor is low (lean), the A/F correction value increase, and when the voltage is high (rich), the correction value decrease.

    Example 4 : Boost control solenoid

     When the throttle is released, the boost pressure solenoid operates momentarily, and the negative pressure seems to open the turbine wastegate.

    Example 5 : Coolant temperture

     When the road is congested (when starting and stopping repeatedly), the water temperature gradually rises. It seems to be less than about 90 degrees Celsius when running normally. The water temperature drops as soon as you run.

  • Download and install

    Download the zip file from the link below and extract it to any folder on your PC. I am not using the registry. Configuration values are saved in the "select_monitor.ini" file in the application installation folder. The .ini file cannot be customized for other SUBARU cars.(Support for other car models may be available upon request.)

    SUBARU Select Monitor for Windows (Impreza WRX edition)
    Build 240224 Right click to download Change ini file folder.
    Build 240212 Right click to download Installer available.
    Build 230318 Right click to download
    Build 230307 (Beta) Right click to download

    If you download the ROM data (bin) of the ECU from the link below, you can display the fuel and ignition timing map. It's safer than actually reading from the car. Put the downloaded file in the same folder as the software. You will be able to select it in the combobox of MAP tab.

    Link to ECU Rom Images (  (A separate window will open.)

    Current supported ECU/TCU ROM ID and Correspondence in the future

    The currently supported Impreza ECU ROM IDs are as follows. If the ROM ID is not registered, you can use only MAP displaying with pre-downloaded ROM data and reading of ROM data function. If you send me your ROM ID with your vheicle information and whole ROM data, I will register your ROM ID.

    ROM IDMarkerLabelMCUYearOriginVehicleTypeConfirmed
    744011JECSW9M377911994JDMWRXEJ20 Turbo
    744014JECSZ4M377911995JDMWRXEJ20 Turbo
    744017JECS??M377911994JDMImpreza?EJ20 Turbo
    74401AJECSZ5M377911995JDMWRX RAEJ20 TurboX
    74401EJECS7KM377911996JDMWRX STi RAEJ20 Turbo
    744042JECS7KM377911994UKWRXEJ20 Turbo
    A30113JECSY5M377911998JDMWRX STi RAEJ20 TurboX
    A30113JECS??M377911997EDMImpreza GTEJ20 Turbo

    The currently supported Impreza TCU ROM IDs are as follows. If the ROM ID is not registered, you can use only reading of ROM data function. If you send me your ROM ID with your vheicle information and whole ROM data, I will register your ROM ID.

    ROM IDMarkerLabelMCUYearOriginVehicleTypeConfirmed

    About the USB-Serial cable

    The select monitor protocol for Impreza is 5V TTL level asynchronous serial communication (UART).A USB-to-serial conversion cable is required for this communication on a Windows PC. Because I need to use same serial communication program with SSM for SVX, I need to use same cable for Impreza. The SSM connector for first generation Impreza (~'96) is the same 9-pin square connector as the SVX. On the other hand, the middle generation ('97-`98) uses the same connector as ODB II. However, although shape of the connector is the same as ODB II, nothing is connected to the pins used for CAN, etc., and asynchronous serial transmission and reception are assigned to the two vender reserved pins. Therefore, the same cable used for SVX can use for first and middle generation of Impreza. Last generation of Impreza uses OBD II and not same as these cars.
    You can download the schematic of this cable on this page, so you can create it yourself. (If there are many requests, I will consider selling it.

    The cables used in this software are basically the same as for SVX. (But don't voltage level shift for '92 SVX. I will not work). I think that a cable using FT-232R can be used without problems. A similar USB serial cable seems to be sold by a company that provides software called EvoScan, but this software uses the FT232R's native driver (same basic The same program is used to read the data). Therefore, it will not work properly unless it is a cable using FT232R.

    Rev1.3 For middle generation GC8/GF8 Impreza Download the schematic in PDF
    I found a description that the VAGKKL cable can be used, so I tried it. The pin connection can be changed with a switch, and it seems that it works in FIAT, but unfortunately it not works in Subaru. After I investigate the circuit, the output pin and input pin are tied together and it is for half-duplex communication. The voltage level of the signals are 12V. Since it not compatible with SSM, I removed unnecessary parts and tie FT232C pin into 12 and 13pins directly. It seems work well. This cable is inexpensive, so it may be good to use it as a material for SSM cable.

    Schematic for modifying VAGKKL cable Download the schematic in PDF

    Although it is unconfirmed, the EvoScan cable may be used.

    I have some parts in stock, so I might make a cable if requestedif you can't make it yourself, please contact us directly by email. Although it is unconfirmed, the EvoScan cable may be used

    About Disclaimer and Updating

    In order to avoid trouble, I describe the minimum description of the license.

    Software License
    1. Prohibition of commercial use
      Use of the software is for personal purposes only. No commercial use is permitted.
    2. Licence
      This software may not be sublicensed, transferred or sold without permission. Free to distribute, rent or lend, copy or translate.
    3. Attribution of rights
      All title and ownership of this software and any copies thereof remain with "Grove Design Service".
    4. Disclaimer of warranties and disclaimer
      1. This software is licensed as-is. "Grove Design Service" makes no warranties of any kind, express or implied, including warranties of merchantability and fitness for a particular purpose, with respect to the Software.
      2. I am not responsible for any damages (including but not limited to lost profits and other consequential or incidental damages) arising from the use or inability to use this software.
    5. Support and updates
      This software was created from information provided by external sources and information contained in service manuals. There may be errors in the information, and parts not described in the materials are created by guesswork. Please let me know when you use it and find something does not works correctly. I will fix the software once reported information is correct or suitable, but I cannot promise when to update the software. Please note that I may not be able to respond immediately.

    Development cooperation and contact information

    I would appreciate it if you could help me with the development of this software. We own a mid generation GC8 MT, but we do not have an first generation of GC8 or AT car. There doesn't seem to be any information about AT's TCU on the net. If you cooperate, I think that I may be able to support TCU as same as SVX. Contact information is below. In addition, I have no plans to support last generation of GC8 Impreza ('99~) becase there are many another ODB II software.

    It took me some effort and money to design this software and cable. I can't decide how much maintenance I should do for the release of this software, but I decided to make this software a donationware. The method of donation shall be an E-mail type Amazon gift or PayPal. Donation amount is arbitrary. Please donate any amount if you use it and find it valuable. Email: Please contact the same email address for bug reports and improvement requests.

    Click Icon to PayPal me

    I thought about posting a link to Amazon Gift, but it seems that it is judged as a spam site (fraudulent site). Sorry to trouble you, but please search for "Amazon Gift Cards (E-mail type)".

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