Ecm failure? Help

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Jsbikerboy92

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Feb 23, 2019
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I just bought a 1985 Buick LeSabre. It has a 5.0 v8. When I bought it from my computer worker it had the battery dissected. He brought it to the yard and stored it there for about 3weeks. It has Ben sitting since 2015. Anyways soon as I connected the battery the check engine light was on instantly. I went to check the obd1 port and there was no power. I found a blown fuse. When I put the new fuse in the port the computer started smoking. So I disconnected it. The car runs the same without the computer plugged in at all. Is that normal? It has a slight misfire and slight shake at idal. Check engine light doesn't do nothing different either.
 

Clone TIE Pilot

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Disconnecting the ECM should send the car into limp mode, which means the carb defaults to full rich and only a little ignition advance. Plus there would be no trans lockup. Generally ECMs don't go bad, so there is probably a short to ground in the wiring sonewhere that fried the ECM. The big question here, is what the PO did to the wiring. POs just love to butcher car wiring in bizarre ways, which is they often sell their botched project.
 
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Jsbikerboy92

Not-quite-so-new-guy
Feb 23, 2019
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View attachment 106888 View attachment 106888
Disconnecting the ECM should send the car into limp mode, which means the carb defaults to full rich and only a little ignition advance. Plus therd would be no trans lockup. Generally ECMs don't go bad, so there is probably a short to ground in the wiring sonewhere that fried the ECM. The big question here, is what the PO did to the wiring. POs just love to butcher car wiring in bizarre ways, whichbis they often sell their botched project.
Disconnecting the ECM should send the car into limp mode, which means the carb defaults to full rich and only a little ignition advance. Plus therd would be no trans lockup. Generally ECMs don't go bad, so there is probably a short to ground in the wiring sonewhere that fried the ECM. The big question here, is what the PO did to the wiring. POs just love to butcher car wiring in bizarre ways, whichbis they often sell their botched project.



So it does feel sluggish on take off and does smell like it's running ritch. I didn't notice anything wrong with 3erd gear.. where do you recommend I start? The car looks untouched as far as wiring goes. It's all looks in great shape.. but the automatic door locks do go crazy at all times.. running or not.. every 10 seconds they unlock or lock. Something to do with it?
 

airboatgreg

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Yes you have a fried ECM. Not going to run right until we get that working. Most common thing I found for frying a computer is a shorted relay. First look at the wiring harnesses for other work as previously mentioned. Look on exhaust for wiring that is burnt and shorted out. If all looks good get a wiring diagram and acquaint yourself with all relays and solenoids. Then it is ohm meter time to check them. I would go to relays first as there is not that many. On the most part the ECM controls the return (Ground) to turn them on and off. If all solenoids and relays test good then you will need to go to the ECM connector and do a pinpoint test.
 
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Jsbikerboy92

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Feb 23, 2019
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Yes you have a fried ECM. Not going to run right until we get that working. Most common thing I found for frying a computer is a shorted relay. First look at the wiring harnesses for other work as previously mentioned. Look on exhaust for wiring that is burnt and shorted out. If all looks good get a wiring diagram and acquaint yourself with all relays and solenoids. Then it is ohm meter time to check them. I would go to relays first as there is not that many. On the most part the ECM controls the return (Ground) to turn them on and off. If all solenoids and relays test good then you will need to go to the ECM connector and do a pinpoint test.
I will be checking it out today. Keep updates
 

rfpowerdude

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Jul 15, 2013
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I have a few 1228330 ECMs for 1988 Olds Cutlass application. Not sure if one would help...
 
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Bonnewagon

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I had a '95 LeSabre parts car that would blow the ECM fuse. I would put one in and it would run fine but after a short time it would pop again. I never found the cause so I junked it. If course when the truck came for it it drove perfectly right up the onto the flat bed. For an '85 why not just back-fit non-CCC parts?
 
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Jsbikerboy92

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Feb 23, 2019
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I went ahead and ordered a ecm from eBay so I can try it. I'm just worried about blowing that one out as soon as I receive it on Friday. My ecm is a different number.
Is it normal for this car to run decent with the computer completely off the car?
 

Bonnewagon

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The ECM was mainly for emissions under lean operation. Without it the settings are rich which works in winter. Find out why the fuse blew and test all the wiring before sacrificing the new ECM.
 
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