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ok, First let me introduce myself, My name is Nick. I recently bought an 89 900t convertible for my neice. it was cheap and ran..but needed work. long stry short..now it doesn't run.
Now I actually am a pretty good wrench, but i have never worked on a Saab. (VW/audi/porsche) I have a problem where the fuel pumps are not running. I jumped the relay(s, there are 2 next to each other ) and got the pumps going. Turns out after crankling and checking I am getting no pulse to the injecters.
Car has spark
good battery
known good/new fuel pump relays installed
So i order a computer (used ) a 02800000570 for the car and get it , plug it in and voila... the noid light is on...but it won't go off, the injecters are wide open, floods the cylinders to hydralock in like 5 seconds...bad ecu, right?

anyone know if i can use a later (and much easier to get) ecu from say a 90 900 turbo? 02800000948? help this thing is killing me....i cannot even get a bentley ...nla, none available anywhere.
Thanks in advance
 

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Welcome to Saab Central.

The '89 ECU's are known to be problamatic. As someone else can probably elaborate, I think the 89 ECU's were sourced out by Saab and had cheap/inferior componants. I'm 99.9% sure you can trade out the ECU with a later version turbo's..but I could be wrong...there were a few ignition changes throughout the years...the part number should be the same. If you've got a pull-a-part or local junkyard that is where I would start. I had similiar problems out of an ignition control unit, (the little black unit attached to the inner fender next to the air intake)...might be worth checking out as well.

Ebay is a good place to source a Bentley..I found one for 10 bucks. Good Luck!
 

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Discussion Starter #3
will a ecu from a 9000t work? i was looking at a chart that had all the ecu and amm for the various cars
 

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Any 900 ECU from a turbo from 90-93 will work just fine. In a pinch you can also use the 900 ECU from the non-turbo 89-90 (maybe 91 too but don't quote me on that as I'm going by memory). The fuel mapping is a bit different and will lean out a bit on the top end. In a real pinch, an '88 non-turbo will also work, but you're upshift light will not work and again will lean out on top end. Early '89 9000 turbo will also work.
 

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I had the same problem on my 89 convertible. I traced the problem to the grounds at the front right area. Bottom of the radiator. There should be two black grounds with multiple wires and of course the one part of the blue battery ground wire should also be grounded there. If you have rust near that area or the the wires that are connect to them grounds look weathered, get new ground connectors connectors and start cuttin. I found that to be the case on my 900. I just went as far a sanding and repainting the whole engine bay. I was changing the main seal at the time.

Also sknaffi is right, get a Bentley manual. It has a easy to read wire diagram and that was how I traced the problem with the ECU. Saved me a $150+ dollars.
 
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