EMS P15 (red) no +12VDC , reads 3.2VDC on pin 14

KA4HRE

I love flying!
Joined
Oct 28, 2012
Messages
17
let me start by saying I am a VERY HAPPY, long time Dynon customer.  Here's my issue: my red cube stopped reading flow.  was working.  stopped.  0.0 flow reading.  So I've read some threads and saw where I needed to verify +12VDC on Pin 15 (red wire) from EMS.  I read 0.0VDC on this pin.  I read 3.2VDC on Pin 14 (yellow wire) which sounds like close to what I should see.  All readings taken from the EMS harness and with red cube disconnected, because I suspect the cube is fine and that I've somehow lost the +12VDC.  Is there a little tiny fuse in the EMS I may have blown?  Does the cube HAVE to get its +12VDC from this pin?  Can it be powered off of a 3 AMP breaker, for example?  Thank you.
 

dynonsupport

Dynon Technical Support
Staff member
Joined
Mar 23, 2005
Messages
13,226
There is protection on Pin 15 (regulated 12V output), but it can also be damaged. While it's not required that you use Pin 15 to power the fuel flow sensor, it is recommended to use it because it's a REGULATED 12V output, and a typical aircraft "12V bus" isn't very well regulated for powering delicate, expensive sensors like the fuel flow sensor.

I suggest checking out your harness to ensure that the red wire you think is connected to Pin 15 is actually wired to Pin 15. There's more than 1 red wire in an EMS harness.


let me start by saying I am a VERY HAPPY, long time Dynon customer.  Here's my issue: my red cube stopped reading flow.  was working.  stopped.  0.0 flow reading.  So I've read some threads and saw where I needed to verify +12VDC on Pin 15 (red wire) from EMS.  I read 0.0VDC on this pin.  I read 3.2VDC on Pin 14 (yellow wire) which sounds like close to what I should see.  All readings taken from the EMS harness and with red cube disconnected, because I suspect the cube is fine and that I've somehow lost the +12VDC.  Is there a little tiny fuse in the EMS I may have blown?  Does the cube HAVE to get its +12VDC from this pin?  Can it be powered off of a 3 AMP breaker, for example?  Thank you.
 
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