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How to read ECU codes Classic Impreza
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Old 29 Sep 2008, 01:57 AM   #1 (permalink)
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How to read ECU codes Classic Impreza

Manually Reading ECU Codes (Classic Impreza’s only)
On Classic shape Impreza’s only (not Newage) faults can be displayed as pulses of the Check Engine Light. If the Check Engine Light goes out there is no fault.

In order to perform diagnostic (and ECU resets) you will need to connect some wires together under your steering column. Note, the following procedure only works for Classic shape Impreza’s, not for Newage.

Make sure your ignition is OFF
Connect the Black ‘Read Memory’ connectors together as illustrated below at end of page.

Figure 1 - Black and Green Connectors on Classic Impreza
When the Black connectors are connected you are in diagnostics mode. Turn your ignition ON and ‘read’ the ECU code(s) being reported according to the following instructions. Note, you may here relays clicking and your fan starting and stopping - this is normal when in diagnostics mode.

In Diagnostic Mode – No Fault is indicated by the Check Engine Light continuously & evenly flashing on/off (this is also used to indicate the successful completion of an ECU Reset). When finished Dianosing disconnect the Black connectors


Figure 2 - Check Engine Light Pulse Width
The long pulses (1.3 Seconds) indicate Tens and the short pulses (0.2 Seconds) indicate ones. Pulses are separated by Short Pauses (0.2 Seconds), multiple codes are separated by a Long Pause (1.8 Seconds).

The simplest way for an inexperienced mechanic to retrieve codes is to write the codes down in a sort of Morse Code (dots and dashes), and start a new line when you get a 1.8 Second pause (for NEW code), and then add the actual numbers up after code retrieval is completed.

(See Example Below)

--- CODE EXAMPLE, SINGLE CODE ---

1.3 second pulse (10)
0.2 second pause
1.3 second pulse (10….for a total of 20)
0.2 second pause
0.2 second pulse (1…..for a total of 21)
0.2 second pause
0.2 second pulse (1…..for a total of 22)
0.2 second pause
0.2 second pulse (1…..for a total of 23)
(Code 23 — MAF Sensor)

--- CODE EXAMPLE, MULTIPLE CODE ---

1.3 second pulse (10)
0.2 second pause
1.3 second pulse (10….for a total of 20)
0.2 second pause
0.2 second pulse (1…..for a total of 21)
0.2 second pause
0.2 second pulse (1…..for a total of 22)
0.2 second pause
0.2 second pulse (1…..for a total of 23)
1.8 second pause (this means NEW code)

1.3 second pulse (10)
0.2 second pause
0.2 second pulse (1…..for a total of 11)
0.2 second pause
.2 second pulse (1…..for a total of 12)
(Codes 23 and 12, MAF Sensor and Starter Circuit)
Attached Images
File Type: gif classic_test_mode_connector.gif (138.4 KB, 171 views)

Last edited by stiimpreza1984; 08 Jun 2009 at 09:11 PM.
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Old 14 Apr 2009, 09:36 PM   #2 (permalink)
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Re: How to read ECU codes Classic Impreza

hi there its the old shape scoob on a M plate its an inport. the other thing is that before all this trouble started it sometimes wouldnt start up after a run it would just turn over and over then out of the blue it would fire up. would that cause anything to go wrong. thank you for the trouble codes mate.
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Old 14 Apr 2009, 11:28 PM   #3 (permalink)
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Re: How to read ECU codes Classic Impreza

Whats the plugs, leads and coil pack on engine like what codes came up aswell?
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Old 15 Apr 2009, 09:08 PM   #4 (permalink)
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Re: How to read ECU codes Classic Impreza

hi mate i changed the spark plugs bout 4000mles ago the leads look ok bout hard to tell . not check the coil pack didnt think of checking that so i will do. not been able to check the check light flashes will be checking them to as iv been working funny hours this week. will let you no tomo evening thanks for your help so fare
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Old 15 Apr 2009, 11:36 PM   #5 (permalink)
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Re: How to read ECU codes Classic Impreza

Quote:
Originally Posted by 101trev View Post
hi mate i changed the spark plugs bout 4000mles ago the leads look ok bout hard to tell . not check the coil pack didnt think of checking that so i will do. not been able to check the check light flashes will be checking them to as iv been working funny hours this week. will let you no tomo evening thanks for your help so fare
Glad to help any slits or cuts in leads if you run the car on a dark night look at leads if a cut you will see like blue arking that will point the problem if leads, also I find the engine light codes first just to see if a sensor faulty and causing the problem
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Old 17 Apr 2009, 08:47 PM   #6 (permalink)
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Re: How to read ECU codes Classic Impreza

hi mate i done the fault code thing and its come up with Engine speed signal circuit. do you know if that would be something like the camshaft sensor or something along them lines?
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Old 18 Apr 2009, 02:57 AM   #7 (permalink)
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Re: How to read ECU codes Classic Impreza

Good question their lads will help you more on this as getting stuck for words so a code 1 came up I would imagine if it was the camshaft sensor the code 13 would come up sure lads will help you more on this code 1 Scoobypedia | Trusted knowledge for everything Subaru | Knowledge / Subaru Specific Trouble Code Definitions
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Old 07 Jun 2009, 12:23 PM   #8 (permalink)
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Re: How to read ECU codes Classic Impreza

Hi to all,

Do the green test mode cables have to be connected at all times?

Thanks
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Old 08 Jun 2009, 12:14 AM   #9 (permalink)
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Re: How to read ECU codes Classic Impreza

Quote:
Originally Posted by GTTURBO View Post
Hi to all,

Do the green test mode cables have to be connected at all times?

Thanks
No dont connect them leave them disconnected you only connect them if you want to reset ecu but personally if I was to reset my ECU I would leave negative lead off battery for the night heres where you leave them connected only for the reset of ecu Scoobypedia | Trusted knowledge for everything Subaru | Knowledge / ECU Reset
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Last edited by stiimpreza1984; 08 Jun 2009 at 12:20 AM.
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Old 08 Jun 2009, 11:13 AM   #10 (permalink)
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Re: How to read ECU codes Classic Impreza

Thanks stiimpreza1984,

So to read the ecu for error code do you just connect black together??? or both green and black???

Thanks
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Old 08 Jun 2009, 09:08 PM   #11 (permalink)
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Re: How to read ECU codes Classic Impreza

Quote:
Originally Posted by GTTURBO View Post
Thanks stiimpreza1984,

So to read the ecu for error code do you just connect black together??? or both green and black???

Thanks
Just connect the black connectors bud ya
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Old 08 Jun 2009, 09:37 PM   #12 (permalink)
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Re: How to read ECU codes Classic Impreza

cheers pal both the cables were connected when i bought the scooby and have been for some time seems to run a lot better now with them both disconnected. Thought I would have a tinker with it n noticed this info in forum thanks again pal
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Old 09 Jun 2009, 02:16 AM   #13 (permalink)
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Re: How to read ECU codes Classic Impreza

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Originally Posted by GTTURBO View Post
cheers pal both the cables were connected when i bought the scooby and have been for some time seems to run a lot better now with them both disconnected. Thought I would have a tinker with it n noticed this info in forum thanks again pal
No bother glad to help
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