96-99 Legacy 2.5L DOHC ECU Discussion

[bubba2533]

I have a ECU and wire pigtail from a Legacy. Not sure exactly what year but in the range of 96-99 and it has the 2.5L DOHC engine. This is very similar to the 98rs ECU (I won't say identical because I don't know if that is entirely true.) I found the FSM PDF from a simple google search, but I have a few wires that are not accounted for.

There are 3 wires that do not have any identification in the wire diagram. They are PIN's 91-93.
(The 3 Wires that I did not know are connected to the OBD2 Port)
I would like to find out what these individual wires are used for and what they are called.

Couple Pictures of the inside of the ECU:



Here is everything that is on the ECU cover.

------------------------
DU7 83
83
22611 AD68B
JA 18000 DU7 9305
------------------------

[bubba2533]

PIN #_______Description______Wire Color
1 - Control Unit Power Supply__[Yellow/Blue Stripe]
2 - Control Unit Power Supply__ [Yellow/Blue Stripe]
3 - Knock Sensor Signal __[White/Silver Band]
4 - Fuel Tank Pressure Sensor Signal__ [Yellow/Blue Stripe/Silver Band]
5 - MAF Signal__ [White/Silver Band]
6 - TPS Signal __[White/Black Stripe/Silver Band]
7 - Camshaft Position Sensor Signal (+) __[Dark Green/Silver Band]
8 - Crankshaft Position Sensor Signal (+) __[White/Silver Band]
9 - Empty
10 - Fuel Tank Pressure Control Solenoid Valve __[light Green/Silver Stripe/Silver Band]
11 - Empty
12 - Empty
13 - Idle Air Control Solenoid Valve (Closed End) __[White/Yellow Stripe/Silver Band]
14 - Idle Air Control Solenoid Valve (Open End) __[Black/Silver Band]
15 - Pressure Sources Switching Solenoid Valve __[Yellow/White Stripe/Double Silver Band]
16 - Fuel Injector #4 __[Blue/Black Stripe/Double Silver Band]
17 - GND (Control Systems) __[Black/Red Stripe/Silver Band]
18 - GND (Control Systems) __[Black/Red Stripe/Silver Band]
19 - GND (Power Supply) __[Black/White Stripe/Silver Band]
20 - GND (Sensors) __[Red/Yellow Stripe/Silver Band]
21 - Fuel Tank Pressure Sensor Power Supply __[Red/Silver Stripe]
22 - Engine Coolant Tempurature Sensor __[Black/Yellow Stripe/Silver Band]
23 - Front Oxygen Sensor Signal __[Black/Silver Band]
24 - Rear Oxygen Sensor Signal __[Black/Silver Band]
25 - Fuel Tempurature Sensor __[Red/Blue Stripe/Silver Band]
26 - Atmospheric Pressure Sensor __[Dark Green/Silver Band]
27 - Fuel Level sensor __[Brown/White Stripe/Silver Band]
28 - Camshaft Position Sensor Signal (-) __[Red/Silver Band]
29 - Crankshaft Position Sensor Signal (-) __[Black/Silver Band]
30 - Empty
31 - A/C Relay Control __[Blue/Orange Stripe/Double Silver Band]
32 - Fuel Pump Relay Control __[Purple/Double Silver Band]
33 - Empty
34 - Empty
35 - Vent Control Solenoid Valve __[Brown/Yellow Stripe/Silver Band]
36 - Empty
37 - Rear Oxygen Sensor Heater Signal __[White/Blue Stripe/Double Silver Band]
38 - Front Oxygen Sensor Heater Signal __[White/Double Silver Band]
39 - Back Up Power Supply __[Red/Double Silver Band]
40 - Ignition Control #3 / #4 __[Yellow/Purple Stripe/Silver Band]
41 - Ignition Control #1 / #2 __[Yellow/Blue Stripe/Silver Band]
42 - GND (Oxygen Sensor Heater) __[Black/White Stripe/Silver Band]
43 - Empty
44 - Fuel Injector #3 __[Blue/Red Stripe/Double Silver Band]
45 - Empty
46 - GND (Power Supply) __[Black/White Stripe/Silver Band]
47 - Empty
48 - Empty
49 - Empty
50 - Empty
51 - Empty
52 - Empty
53 - GND (Mass Air Flow Sensor) __[Pink/Silver Band]
54 - Shield __[Gray/Silver Stripe]
55 - Empty
56 - Shield __[Black/Green Stripe/Silver Band]
57 - Shield __[Gray/Blue Stripe/Silver Band]
58 - Malfunction Indicator Lamp __[Red/Green Stripe/Double Silver Band]
59 - Empty
60 - A/C Switch __[Brown/Yellow Stripe/Double Silver Band]
61 - Empty
62 - Empty
63 - Self-Shutoff Control __[light Green/Silver Band]
64 - Engine Speed Output __[Black/Blue Stripe/Silver Band]
65 - Empty
66 - Empty
67 - Empty
68 - Empty
69 - GND (Injectors) __[Black/Yellow Stripe/Silver Band]
70 - Fuel Injector #2 __[light Green/Double Silver Band]
71 - Egr Solenoid Valve __[Black/Pink Stripe/Double Silver Band]
72 - Purge Control Solenoid Valve __[White/Blue Stripe/Double Silver Band]
73 - Radiator Fan Relay 2 Control __[Dark Green/Red Stripe/Double Silver Band]
74 - Radiator Fan Relay 1 Control __[Red/Blue Stripe/Double Silver Band]
75 - Empty
76 - Empty
77 - Empty
78 - Empty
79 - Empty
80 - AT Diagnostic Input Signal (Not On Manual Car) __[Pink]
81 - AT/MT Identification __[Black/Red Stripe/Silver Band]
82 - Neutral Position Switch __[light Green/Black Stripe/Silver Band]
83 - Vehicle Speed Sensor 2 __[Dark Green/Black Stripe/Silver Band]
84 - Test Mode Conector __[Blue/Silver Band]
85 - Ignition Switch __[Yellow/Silver Band]
86 - Starter Switch __[Red/Yellow Stripe/Double Silver Band]
87 - Empty
88 - Empty
89 - Empty
90 - Empty
91 - OBD2 PIN-5 __[light Green/Red Stripe/Silver Band]
92 - OBD2 PIN-4 __[Dark Green/White Stripe/Silver Band]
93 - OBD2 PIN-10 __[Orange/White Stripe/Silver Band]
94 - GND (Ignition Systems) __[Black/Double Silver Band]
95 - GND (Injectors) __[Black/Yellow Stripe/Silver Band]
96 - Fuel Injector #1 __[Brown/Double Silver Band]

[log1call]

Hi,
   the wires at 91 and 92 are the right colour to be the rx and tx which we read at the subaru select connector.

[bubba2533]

I thought this was the wire used to read the ECU, But I don't know that much.

84 - Test Mode Conector __[Blue/Silver Band]

[log1call]

Hi,
    the test mode connector is the wire you connect under the dash to get the "check engine" light to flash trouble codes.
 The other two are what the subaru select monitor communicates over.

[bubba2533]

I just got a breadboard and a 12V DC power source in the mail. I plan to hook up my ECU that I got from the junkyard. I found out that the ECU I have is most likely from a 99 Legacy Outback with a 2.5L engine. I still need to get a cable to connect the ECU to my Computer. I am not sure where to get it or what exactly to get.

[log1call]

Well I'm not sure about your American models but that might be a OBD2 mightn't it?

 If it is using the ssm protocol then it is easy to make a rs232 chip adaptor. I have one I made years ago and it plugs into a serial port and now days I run it through a usb to serial adaptor so I can use some of the more modern software. I've attached a circuit diagram. I am using a nine pin serial plug to the laptop but the pin connections are easy to convert from the twenty-five pin one.

 I found that it pays to keep the wires as short as possible between the cars ecu and the adaptor. Once the signal has been through the chip it seems fairly immune to signal loss or interferance and you can have a long extension, or usb to serial adaptor, between the sr232 chip and the laptop.

[bubba2533]

Yes it is OBD2. Will that work for my ECU even if it is OBD2?

[log1call]

It will work, but it will take more user input and it will not work with as many pieces of software as something like an Elm chip based adaptor would. If you just want the data then the easiest way is to get a OBD2 reader and some software to go with it.
 
 I believe the Evoscan will work with that adaptor I suggested and OBD2 as long as you get a usb to serial adaptor.  Have a read up, the Evoscan software is primarily for mitsubishis and only has limited support for subaru at the moment. If you are wanting to discover your own data addresses then it should be fine. I'm sure Phil will be able to help there.

[b3lha]

As far as I know, the early OBD2 ECUs support the OBD2 protocol and the SSM protocol (for compatability with the dealers existing select monitors). They use some spare pins of the standard OBD2 connector for the SSM wires. See the pinout on www.vwrx.com.

You will need a different type of interface cable depending on whether you want to connect to the OBD2 or the SSM wires. You may want to try both methods

SSM to serial adapter: http://www.alcyone.org.uk/ssm/sma.html
OBD2 to serial adapter: http://hem.passagen.se/tomasf/obd2/

Then you will need some software to talk to the ECU using the appropriate protocol. Depending on what you want to do, there may be some existing software on the net. Otherwise you will have to write it yourself.

SSM protocol: http://www.alcyone.org.uk/ssm/protocol.html
Subaru OBD2 protocol: http://code.google.com/p/ecuexplorer/downloads/list

I'll be interested to hear what you find out.

[bubba2533]

Ok, so if the SSM uses the same wires as OBD2. Log said that 91 and 92 were the right colors for the SSM, bu which one is which? One wire Transmits and the other Receives.

b3lha, do they sell each of those adapters? I don't really have the time or the resources to make them, so if I could buy them both then I can start learning how to setup the ECU on the test bench and play around with it.

I don't have any experience in programing or much electrical work at all, I know just some basics.

I would mainly like to get the ROM from the ECU I have then learn how to start picking it apart. I have a 97 Impreza L 2.2L, they come with the same ECU plug as the 96-99 Legacy's and I would like to pull the ROM from that ECU and compare it with the 2.5L one. But this may take some time seeing as I am not very knowledgeable in this subject.

[b3lha]

I've never seen an OBD2 ECU so I'm just speculating here.

The ECU uses different wires for SSM and OBD2. In your pinout above, you only have 3 wires marked. So perhaps yours only does OBD2. You will have to trace the wiring between your ECU and OBD2 plug to be sure.

The OBD2 pinout is something like this:

5: Ground
7: ISO 9141-2 K line
12: SSM Transmit
13: SSM Receive
15: ISO 9141-2 L line
16: +12V

It seems to me that the three wires in your pinout are either SSM Transmit, SSM Receive and Ground or their OBD2 equivalents K-Line, L-Line, and Ground.

I suggest you try the "Evoscan 9pin/16pin DataLogger Cable". It can supposedly connect to OBD1 and OBD2 Subarus.

[log1call]

I would suggest you buy the plug/cable that will fit your car. I'd even go so far as say read your car first, then when you know how to connect to that try the bench ecu.
It will simplify getting your first laptop/adaptor/software set up if you are absolutely sure the car is wired and going right.

I'd also use the OBD2 if that is an option.

[bubba2533]

Well, I don't have a laptop and I really don't have the money for one right now. I am in college and I really shouldn't even be spending money on a cable or software, but I got the ECU and harness pigtail for free and I am really interested in this project so I would like to help out as much as I can without breaking the bank.

I would like to use the OBD2 port also, and the Evoscan software looks like it would be fun to play with.

Any info or comments about my situation would be welcomed

[log1call]

Ok, get all the parts and make that circuit I posted. It doesn't need the connector to connect to your ecu on the bench. I think those parts will cost... bugger all. Make sure you do not get sold a surface mount rs232 chip, you need a dip(double inline pin) type, they are much bigger and easier to solder.  Solder that up and mount it on a hunk of plastic with holes drilled in it. Plug it into your serial port and it will read the older models of subarus. If you want to use it to read that ecu you might have to buy a usb to serial adaptor which also cost bugger all. I think fifty of my Kiwi dollars gets it all, parts and usb adaptor, should be about thirty dollars for you. OR else have a look at Phil's links to some new usb cables that have a chip built into them.
 Perhaps you can get the science teacher to help out with the electronic bit.