# DMOC 445 Contactor Not Closing



## TheSGC (Nov 15, 2007)

What are you using for a +12v supply for the DMOC? I have not had a chance to look at a DMOC, but I've repaired many UMOCs that needed the contactor dismantled and cleaned. 

You need to make sure you 12v supply is solid, if its too low the DMOC wont show an interface, or close the contactor. 

The contactor also wont close if the batteries are under the Low Voltage setting of the DMOC.


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## opusengineer (Jan 22, 2014)

I'm using a typical 12V car battery. I think it has about 650 Cranking Amps. I'll check the voltage again (it has been cold lately), but it used to be right at 12V.
One possible issue may be that it's wired through a switch that also controls the BMS... I'll rig up a direct connection to see if this helps.

Thanks for the comment!


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## TheSGC (Nov 15, 2007)

opusengineer said:


> I'm using a typical 12V car battery. I think it has about 650 Cranking Amps. I'll check the voltage again (it has been cold lately), but it used to be right at 12V.
> One possible issue may be that it's wired through a switch that also controls the BMS... I'll rig up a direct connection to see if this helps.
> 
> Thanks for the comment!


12v for a car battery is pretty low, it should be around 12.6-12.8v after a full charge.


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## opusengineer (Jan 22, 2014)

Ok, I'll try charging the 12V battery to 100% and see if that helps. It's currently at 11.91V and it's cold outside.
New information for those who are kind enough to read this and offer possible solutions:
ccShell isn't working either (even after setting the affinity to just one processor).
Still no response after disconnecting the Azure Forward/Reverse switch and directly connecting pins 19 & 29 (as suggested in another post).
I re-wired the 12V battery to be much closer to the DMOC, but no help there either.
I double checked the HV voltage (still at 331V) at terminals.
Potbox resistances are all good.

Key questions/differences from last time this happened:
Resistance between Pin#29 and Pin#20 is now 10.6ohms (not 2.4ohms)...
Should Pin #12 be grounded to the frame? (it is currently connected)
Does the pedal/potbox need to be isolated from the frame? (it is currently not isolated)

Thanks!
Josh


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## rclugnut (Aug 11, 2011)

Pin 20/29 shouldn't be connected from what i can tell. I'm attaching a few manuals i've collected... It's been a while since i've worked with this system so it's hard to say.


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