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Power loss between GRT engine Monitor and GRT EFIS

J

Jonathan Alvord

Well Known Member
I have this little gremlin that is driving me crazy. Has been an issue for a year or so. Thought I had it tracked down to a faulty rectifier diode but may not be the issue. Have ordered new Garmin 355 and was hoping it would come in so installer could address issue, hopefully it will come in Nov.

Anyhow. my Engine Monitor show 13.5v when running but the EIS is usually 10-11v and sometimes even around 9. It is not an issue until trying to transmit when the EIS will occasionally loose power and reboot. I don't think it is the alternator as it is charging the battery. all the lights work. its just getting full power to the EFIS that is the issue.

Jon
 
Can you clarify the English in your post? In GRT parlance the EIS is the engine monitor. Did you mean EFIS?
It sounds very much like you have a poor connection somewhere. With the EFIS powered up, take a voltmeter and make measurements all along the power system, starting at the battery, thru the master, avionics buss if any, thru the circuit breaker/fuse, at the power pin for the efis. There should be no measurable (with a cheap voltmeter) drop anywhere. You may have a bad crimp somewhere, or a defective circuit breaker or switch, etc.
13.5 volts is low for modern alternators/regulators, so there may be an issue there, too.
 
Last edited:
BobTurner said:
Can you clarify the English in your post? In GRT parlance the EIS is the engine monitor. Did you mean EFIS?
It sounds very much like you have a poor connection somewhere. With the EFIS powered up, take a voltmeter and make measurements all along the power system, starting at the battery, thru the master, avionics buss if any, thru the circuit breaker/fuse, at the power pin for the efis. There should be no measurable (with a cheap voltmeter) drop anywhere. You may have a bad crimp somewhere, or a defective circuit breaker or switch, etc.
13.5 volts is low for modern alternators/regulators, so there may be an issue there, too.
Click to expand...

Thanks for the quick response.

Yes the EIS is the GRT engine Monitor which shows same voltage as battery. The only area of concern is the EFIS voltage which is constantly low. The Alternator was replace two years ago with Plane Power Alternator and showed exactly same charging through the Engine monitor and with voltmeter when last check. I suspect I will need to find the power wires to the units and trace them back.

Jon
 
I was reading somewhere in the GRT literature that if you have low voltage you have too many things grounded in one place. I would try to ground the EFIS separately, by itself and see if that helps.

Jonathan Alvord said:
I have this little gremlin that is driving me crazy. Has been an issue for a year or so. Thought I had it tracked down to a faulty rectifier diode but may not be the issue. Have ordered new Garmin 355 and was hoping it would come in so installer could address issue, hopefully it will come in Nov.

Anyhow. my Engine Monitor show 13.5v when running but the EIS is usually 10-11v and sometimes even around 9. It is not an issue until trying to transmit when the EIS will occasionally loose power and reboot. I don't think it is the alternator as it is charging the battery. all the lights work. its just getting full power to the EFIS that is the issue.

Jon
Click to expand...
 
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