I have found out that below 13 volt the VM1000 stops working. When speaking to the support people at Vision I have been told that the  VM1000  should work down to 9 volt. I have tried to get a hint what to do from this support people but they are not so interested in my problems. Even when asking where to send it to get it fixed have not resulted in an answer. Has anyone out there had a similar problem and are villing to give me a hint how to fix it. I have been asking the Vision company for a schematic but they refuse to give it to a user. I have some experience in repairing  electronic equipment and I should appreciate very much if anyone could give me an advice how to fix this problem.

Christer,

 

Can you independently (non-VM) measure the bus voltage that is supplied to the VM instrument? I.E. a separate voltmeter on the supply line.

 

I have older 12VDC VM equipment (EPI 800) that definitely restarts after the voltage dips below 9 VDC, although this only happens at engine start.

 

If your VM is on an "essential bus", separated from the main bus by an isolation diode, then that essential bus will be operating at a lower voltage than the main bus.  Depending on the load carried by the essential bus, the voltage drop can be significant and it should be monitored.

 

Another possibility is poor grounding for the VM.