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1990 corvette ecu problems

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Old Dec 6, 2008 | 08:46 PM
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Default 1990 corvette ecu problems
ok so my freind got a 1990 corvette and the guys said the computer was fried so we put a new ecu in it but it wont fire. we tryed to reset the security with this key method we found. any ideas
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Old Dec 6, 2008 | 09:41 PM
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How did they decide the ECM was bad.
Does it crank?
Did you use noid lights to check for injector pulse?
Does it run a few seconds and stop?
Did you measure the pellet resistance and put an resister in to replace it in the harness?
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Old Dec 6, 2008 | 10:39 PM
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the guy he got the car from said it was bad and had a new one just never put it in
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Old Dec 7, 2008 | 12:45 AM
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Central timer modules (BCM) go bad in those too. Have to do some testing & see.
Those will get the security light going too.
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Old Dec 7, 2008 | 07:15 AM
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90 vette should not have a BCM, they were TPI motors, that used a VATS module to operate the the anti-theft on the starter and the ECM
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Old Dec 10, 2008 | 07:40 PM
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ok we started messing with it and it will it will turn over but wont start when u roll the windows down will turning the key. its not firing and the fuel pump wont turn on
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Old Dec 10, 2008 | 08:41 PM
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is the correct prom chip in the computer?
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Old Dec 10, 2008 | 10:09 PM
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yes it. but if it goes bad will it cuase it to do that
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Old Dec 10, 2008 | 10:15 PM
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Did you check for pulses with noid lights on the injector plugs?
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Old Dec 10, 2008 | 10:17 PM
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how do u do that. srry still trying to learn this crap.
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Old Dec 11, 2008 | 10:37 AM
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Originally Posted by perrco
how do u do that. srry still trying to learn this crap.

Noid lights are little plastic plugs with an LED in them, that tells you if the injector is getting a fire pulse, when you plug them in to the injector plug. If you have a Harbour Freight near you, you should be able to buy a set for $20, if its a VATS issue there will be no injection pulse. Did you check the fuel pressure? We all have to learn sometime
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Old Dec 11, 2008 | 08:45 PM
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Originally Posted by perrco
yes it. but if it goes bad will it cuase it to do that

yes it would but I can tell you I have NEVER seen one go bad just missing when ecms get swaped out.
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Old Dec 12, 2008 | 04:04 PM
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"but wont start when u roll the windows down will turning the key."
Huh??????
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Old Dec 12, 2008 | 06:48 PM
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ok it will only turn over when u hit the window button while u turn the key. but it still wont start.

we still cant figure it out
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Old Dec 12, 2008 | 09:41 PM
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Default Before..
Originally Posted by perrco
ok it will only turn over when u hit the window button while u turn the key. but it still wont start.

we still cant figure it out
you condem the ECM, I'd be looking at some wiring diagrams, and see how there may be a connection to the power window circuit.
There's likely some interface that powers the window circuit only when the key is in the on position??
Windows work w/ key in run position?
Windows work w/ key off?
A trip to the Vette forum may be in order....
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