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Car dies; ECM smokes by snyderman
Started on: 07-11-2013 10:19 PM
Replies: 4 (241 views)
Last post by: snyderman on 07-15-2013 09:42 PM
snyderman
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Report this Post07-11-2013 10:19 PM Click Here to See the Profile for snydermanSend a Private Message to snydermanEdit/Delete MessageReply w/QuoteDirect Link to This Post
Hi I'm a little frustrated and need your help. I moved the location of my battery by replacing the cables (I put in in the back of the car in the well) Hooked up a new battery and it ran fine. Tried to start it a few days later and it turned over but would not start. But there was power to everything else. The only thing I noticed that would not work were the headlights as they would not open up (they usually do). So assuming the battery was not fully charged and that was preventing me starting it, I boosted the car with my other vehicle and the car started up right away and the head lights worked. I removed the booster cables - everything seemed fine and a minute later the car died. I saw smoke in the ECM and removed it from the vehicle.

I assume I need an new ECM and suspect it's because I over charged it when I boosted the car. Any ideas on what cause it not to start and the headlights not to open when I tried to start it with a new battery? Thanks in advance. Gary

[This message has been edited by snyderman (edited 07-11-2013).]

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phonedawgz
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Report this Post07-12-2013 11:13 AM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post
The big round red thing is an overvoltage spike killer called a Varistor. A high sustained over voltage condition can kill the varistor and the ECM. Most likely however is your ECM still works. You did however kill it's voltage spike protection. Use it if you need to and if it works, but plan on replacing it before it strands you.

$40 plus shipping for a used 1227170 ECM from me. email me if you are interested - gofast@reddevilriver.com

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Define 'boosted'. Just a normal jump start or something else?

From what I see of your ECM it experienced a significant over voltage situation. Perhaps from running without a battery with a flaky alternator. The battery levels out the alternator output. Maybe this was caused by alternator spikes with the battery poorly connected.

Also if in your remote battery set up you are using the frame as a battery return wire, bad connections from the frame to the engine can cause major problems. There are wires in your engine harness that run from the frame of the car to the engine. If your negative battery cable runs to the frame instead of the engine, and the engine to frame connections are not the best, you will burn up those wires in your wiring harness.

[This message has been edited by phonedawgz (edited 07-12-2013).]

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snyderman
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Report this Post07-12-2013 05:36 PM Click Here to See the Profile for snydermanSend a Private Message to snydermanEdit/Delete MessageReply w/QuoteDirect Link to This Post
Thank you ever so much for taken the time for your detailed reply. I since found out that the "new" battery I put in was not topped up and is presently on charge. I will try the "burnt" ecm as soon as it is charged and let you know. I may have a replacement ecm closer to home, but if not, I'll PM you about buying yours. As for the ground connection, it is grounded to the engine with a brand new cable plus there is s smaller wire that grounds to the frame so I don't think it's that.

I'll let you know more when I try to start it.

Thanks again. Gary

P.S. "BOOSTED " was with my pickup truck but I did leave the cables connected for aprox 3 mins as I didn't take them off as soon as it started...

[This message has been edited by snyderman (edited 07-12-2013).]

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phonedawgz
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Report this Post07-12-2013 08:54 PM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post
If you normally jumped the vehicle that would not kill the ECM. Not having a battery connected, or having a dry battery connected however could. Watch the voltage when it starts. Make sure it doesn't go too high.
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snyderman
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Report this Post07-15-2013 09:42 PM Click Here to See the Profile for snydermanSend a Private Message to snydermanEdit/Delete MessageReply w/QuoteDirect Link to This Post
I charged the battery and slapped the old ECM back in and it fired up just fine. I have since replaced the ECM and no troubles. I assume the voltage spike in the ECM came from having both the Fiero and my truck running for 3 minutes before I disconnected the booster cables. I've been told the alternator may have sent to much juice. In any case, I'm back in business. Thanks again.
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