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Re: IAC stop Posted by RS [Email] (#15) [Profile/Gallery] (more from RS) on Thu, 28 Aug 2014 06:07:11 In Reply to: Re: IAC stop, Landjet [Profile/Gallery] , Wed, 27 Aug 2014 20:13:11 Members do not see ads below this line. - Help Keep This Site Online - Signup |
I wish that I could claim credit for tracing it. I found it in a lucky google search one evening looking for "SAAB 900 ECU transistor".
There's a bright guy on the other side of the pond who traced them out when he was trying to save a semi-operative ECU.
The LH 2.4 ECU has a row of 5 power transistors that it uses: 1 for the injectors (all fire at the same time); 1 for the fuel pump relay; 1 for the AIC valve; and I'm not sure what the other one is for.
This picture shows 2 for the AIC so it must be for an LH 2.4.2: http://s29.photobucket.com/user/rodentmaster/media/LHTransistors3_zpsd0ee3e13.jpg.html
Maybe, like certain vestigial organs, it could well be that one of the two AIC transistors lies unused in the 2.4 ECU - the firmware ignores its existence.
Another: http://s29.photobucket.com/user/rodentmaster/media/LHTransistors1_zps481f1cf3.jpg.html
Another: http://s29.photobucket.com/user/rodentmaster/media/LHTransistors2_zpsff534276.jpg.html
I popped open the failed ECU from my '89 and it looks the same, although I don't remember seeing the damper diodes for the AIC coil drivers.
I remembered the google search parameters that can pinpoint the site. One of the first items that pops up is a very good page on a guy's repair of an LH (it's on another SAAB site.) It's well worth the read.
"BDX53C saab ECU replacement"
"ECU Rebuild successful!"
->Posting last edited on Thu, 28 Aug 2014 06:14:34.
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