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Discussion Starter #1
Hello Guys, I ordered My Volt in IAAI auction after small road incendent with RUN and Drive condition. but when it arrived to me in Ukraine, its have full discarded +12v battery. After we loaded battery and clear all errors only one left P0ABC. Cars not drive and all HV system not work. I found dead fuse in MSD. It look like have short circut inside. I removed HV battery and unbolt it. I found two HV Panasonic 120A contactors dead in on position ( allways short). I ordered in ebay used parts, but I don't know why it happened. I worry about hybride motors drive controller/invertor 12643810, if when I install battery with new relays and try to on the car i received same short circut. I checked HV battery conector on module and input impedance +- only 80 ohm. This connector have direct wires with lower connector to AC etc. Maybe anyone want check to me this impedence ? any ideas ? thanks. Roman
 

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Can't answer your question, but a service manual for 2012 Volts is available on this forum somewhere. Would be very helpful for doing in-battery testing etc.
 

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I believe, but not sure, that if the main fuse blows under load the contactors will weld themselves closed from the DC arcing. They normally only open and close at zero load. So if the fuse blew while it was being driven, that would explain the closed contactors. Interrupting a DC circuit under load creates an arc across the contactor points that will not stop like an AC load. Pretty sure I read this in the Volt service manual, that if the fuse blows the contactors will likely need replacement.
 

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Discussion Starter #4
I believe, but not sure, that if the main fuse blows under load the contactors will weld themselves closed from the DC arcing. They normally only open and close at zero load. So if the fuse blew while it was being driven, that would explain the closed contactors. Interrupting a DC circuit under load creates an arc across the contactor points that will not stop like an AC load. Pretty sure I read this in the Volt service manual, that if the fuse blows the contactors will likely need replacement.
Thanks, but it 50x50% but i want be sure for min90% :) I have approx 10 days before new parts arrive to me in Ukraine for check other modules.
 

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Airbag deployment causes the contactors to emergency open, which destroys them. That’s the only reason I’ve ever heard for them to arc and fail like you describe. Were any of the car’s airbags deployed?
 

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Discussion Starter #7
Before I removed battery and found dead contactors, I opened MSD and install aftermarket 200A fuse inside (stock 350A). In moment when I tried put MSD to place (car have disconected +12 batter)i received big BANG with destroyed MSD contacts.
 

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What you need to check for is a loss of isolation in the high voltage system. You will need a volt meter that is made to performed this operation. The meters are not cheap but you have to have one to test the system. Any loss of isolation in the high voltage system while driving will cause the high voltage contactors to open and cause damage. The loss of isolation may have been caused by the charger when it was hit,the charger is part of the high voltage system.
 

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Discussion Starter #9
hi, thanks, but no isolation troubles here! i worry only about hv tiristors/contactors in controller/invertor 12643810. only 80 ohm impedance in +- battery connector, and ~560kohm to ground. I don't want open controller/invertor module w/o any additional info - it waterprof sealed.
 

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Discussion Starter #13 (Edited)
but still need know impedance input +- battery connector. After lokking video, It's look like battery have direct connection to Bi-Polar Transistors and for me 80 ohm it's so very lowe inpedance.
 

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nobody wanna help me?
You are asking questions that require a Volt Technician, most of us are just drivers, some with a little more technical expertise than others. 99.99% have never done what you are doing. Answers may be slow in coming.

Have you thought about buying the service manual?
 

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Discussion Starter #17
thank You, about service manual not sure about i find answer for this question inside. I need good GM mechanic for received answer to this question. Still not found one.
I opened two HV panasonic Contactors and YES contacts are welded inside, not so strong but with melting.
 
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