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Reading fault codes without diagnostic equipment :)


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#1 dnok

dnok
  • LocationElland West Yorkshire

Posted 20 August 2014 - 08:26 PM

Learned this few weeks back (been too busy till now to post) so i thought id share the love. This only works (AFAIK) on classic imprezas and forester SF's or possibly any scoob older than 02. 
I know it works on a 98 forester anyway because we did it today and the guy who taught it me uses it on the classic imprezas :)
Oh by the way as way of a disclaimer by buddy openly admits he got this from a forum a while back but he couldnt remember which one so if someone gets p1ssed because i stole their work then i didnt.... my buddy did lol. 
 
Look under the steering column, under the dashboard not by the ignition (basically break your back by laying with your shoulders on the floor in the drivers footwell with your head under the dashboard and your legs stuck dangerously out of the car into the road for cars to run over :good:) and you will find 2 black and 2 green connectors. Well you will find a couple more lol but its these we are interested in...... 
 
Sorry for blur was hard to get a pic but im sure you can see the shape of them lol.
Attached File  100_3076.JPG   140.45KB   7 downloads
 
When the two black ones are connected your in diagnostic mode. Turn ignition ON and watch the code being flashed.
In diagnostic mode if everything is ok then the Check Engine Light continuously flashes on/off at the same half second on/off rate.
 
Right the following is a direct copy and paste from his notes. (He got this saved in notepad on his phone lol).
 
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)
 
Ok so now youve read the codes and fixed the issue or your just wanting to clear them to see if they come back so....
 
Clearing the codes.
 
Warm up the engine and then turn it off.
Find the two pairs of ECU connectors under the steering column, the black ones, and the green ones. Of course the black ones are probably already connected if youve just done the above. 
With the ignition turned to off join black to black and green to green.
Turn on the ignition but dont start the engine. Press the throttle pedal all the way down then raise it to the half throttle and hold there for five seconds and then take your foot off. (Dunno why but whatever lol)
Engine Check light should now turn on.
Start car and drive for a few minutes and dont let your speed drop bellow 10mph.
ECU is now re-set.
The check engine light should now start to flash the all ok signal, the half second on/off sequence we spoke of before. If it doesnt or flashes another code sequence theres a fault that needs finding.
Turn the car off.
Disconnect the black and the green connectors and your done :good:
 
 
This last bit is also a good one to use if your trying to reset the ecu after mods etc as its the proper way to do it and apparently taking the battery off for x amounts of minutes doesnt always work, although ive always found it to work but whatever.


#2 BushyXT

BushyXT
  • LocationWoodford Green, Essex

Posted 20 August 2014 - 09:10 PM

Yip, I use to have to do that with my MY99 Impreza. The below link has shown me the way many a times in the past...

 

Link: http://www.scoobyped...ReadingECUCodes



#3 dnok

dnok
  • LocationElland West Yorkshire

Posted 20 August 2014 - 11:41 PM

Good link :good: Looks highly likely to be where he got the info from. The code pulse example is the same. 



#4 yasawas

yasawas

Posted 21 August 2014 - 07:12 AM

Have been doing this on my imprezas and legacys throughout the years....now on the fozzy...such a convient way of fault finding!! Thanks subaru :)




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