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Guest Message by DevFuse

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SSM: reading my OBW ECU... stuff to unplug?

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4 replies to this topic

#1 jarl


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Posted 13 December 2012 - 04:49 PM

So... after more than one year delay, I finally put together an adapter to connect my '99 OBW to my laptop. OBDII should be the way to go (and I do have an OBDII dongle already), but it looks like a lot more information is available and ready to be read by using SSM (this is a B11 OBW, by the way... no SSM2 as far as I know).

Anyway... I connected the whole thing and can communicate with the car. The thing is the ROM ID is reported to be A20131, but I can't find any mention of it anywhere. The programs I have downloaded so far know where to look for the relevant parameters for several other ECUs, but not for the A20131 in particular. I can probably hack one of the other profiles and make it work, but comparing the ROM with others may provide more information...

Therein lies the problem :) Dumping the entire ECU takes almost an hour, and during that time I have to leave the switch open without the car running. After a while the fuel pump starts running (leaky injectors?) and who knows what else is energized all that time, but I'm afraid something is going to get fried and/or my battery drained (it's weak to begin with). I think it would be ideal to remove a couple of fuses to try to leave just the ECU powered: fuel pump, maybe injectors, and... ? What else should I disconnect?

#2 presslab


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Posted 13 December 2012 - 06:28 PM

I've left both my Subarus on for the time it takes to download the ROM. It's not a problem. If your injectors leaked, they'd leak down every time you turned off your car as the fuel pump should hold pressure with a check valve.

Put a charger on the battery and dump the ROM. Or start it up and let it idle for 45 minutes. ;)

#3 Fairtax4me



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Posted 13 December 2012 - 11:46 PM

Car manufacturers instruct to put a charger on the battery while updating ECU ROM. Not going to hurt anything by doing that.

Not sure about the ROM ID. Backup the info that's on it, try uploading a few different ones, if none work at least you can go back to the original.

#4 jarl


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Posted 13 December 2012 - 11:57 PM

And... it's dead :P

I connected a charger to the car and downloaded the ROM, but when I stepped off the car I heard the same noise I have heard before. And the battery got drained anyway (was down to 10V or so), so whatever is energized is taking a few amps.

Except it's NOT the fuel pump. :confused: I followed the noise using my stethoscope and it sounds like it's coming from the gearbox or somewhere close to it, but it's NOT the starter motor. Transmission solenoids? Is there something else around there that gets energized when the switch is in the "on" position?

At this point I don't think it's a motor but a solenoid of some kind, and the reason the noise starts after several minutes of having the car "on" is that the volts get so low that the solenoid can not hold correctly and starts to oscillate. What worries me is that the power consumption must be large enough to discharge the battery despite being connected to the charger (admittedly a cheap one), and that power can only be converted into heat. Hopefully nothing got overheated :/

[EDIT] John: you posted while I was writing my message :) Fortunately, I'm not trying to write anything to the ECU at this point... with the volts so low the writing can be a risky endeavor, and the ECU could be bricked. Now I need to check to see if the information I downloaded is correct...

Edited by jarl, 14 December 2012 - 12:01 AM.

#5 Fairtax4me



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Posted 14 December 2012 - 12:08 AM

Idle control motor. You can unplug that and it shouldn't affect your re-program.

Does your charger not have a high charge setting (like 6-10 amps)?
The low settings will hardly even keep up with the draw from the dome lights much less the accessories and ECU. If that's all you have charge the battery overnight, then put it in the car and keep the charger hooked up while you do the download.

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