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Thread: How bad did I kill it?
10-17-2009, 12:54 PM #1
- Join Date
- Dec 2008
How bad did I kill it?
Thanks for this great site. I have a 1987 GMC suburban with a 350 engine. I rebuilt the engine (something I have not done in around twenty years) and think that is probably ok. During installation, I did inadvertently install the battery backwards.
Other than the really awesome fire from the alternator, I am also blowing the "emcb" fuse with the key in the off position. because It is cold and rainy out right now I don't feel like digging into it at the moment. The haynes manual wire diagram indicates I may have taken out the "ECM". Does this seem reasonable? Or is a wire short more likely?
Thanks in advance!
10-17-2009, 09:01 PM #2
An easy way to find out is to unplug the ECM and see if the fuse still blows.Jim
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10-20-2009, 09:06 PM #3
- Join Date
- Dec 2008
I did as you suggested. With the ECM unplugged, the fuse does NOT blow. When I plug it in, it blows right away. This would indicate the ECM is bad, OR something the ECM drives is shorted. The ECM can be had for around $80 so I will take the gamble that it is what is shorting.
Thanks for your help!
10-20-2009, 10:31 PM #4
Nothing is realy "driven" by the ecm- it basicaly tells everything else what to do. I suppose it is possible to have a bad relay that is driven by the ecm signal, but I doubt it. This is a good example of why I still like points, though!
10-21-2009, 08:13 AM #5
Next step is to check the fuse wire to the ECM. With ECM unplugged the wire from the fuse should test open with an Ohm meter. If the wire is open the ECM is probably shorted. If the wire is grounded <Short> then you need to replace the wire or find the short. Sometimes it's easier to just replace the wire rather then trying to find the short but it's up to you. Do not replace the ECM until you have fixed this wire.
10-21-2009, 08:18 AM #6
10-22-2009, 11:36 PM #7
Got me on that one. This is also a good example of why I quit being an auto mechanic in 1995.
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