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E-Mag RPM Not Displaying on Garmin EIS

agsully

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I installed an E-Mag as the left mag in my RV-10 with an IO-540 engine. The all Garmin panel includes two Garmin G3X units with the Garmin GEA 24 Engine Indication(EIS) System. The right mag is a Bendix mag. The newly installed E-Mag appers to function as expected except for the engine RPM displayed on the EIS. The EIS shows an RPM of Zero when the engine is running. The EIS is calibrated as specified for “Electronic Ignition (3 pulses/rev).” The EIS functioned correctly when the UMA Magnetic Tach Sender was installed on the left Bendix mag, which was replaced wih the E-Mag. To determine if the EMag was generating and sending three voltage pulses per revolution to the EIS, a voltmeter set on AC was used to check for voltage pulses per revolution while pulling the prop through by hand. The E-Mag was tested with the voltmeter grounded first to the airframe and then to the engine. In both instances the voltmeter showed three voltage pulses per revolution with the voltmeter connected to the blue wire from the E-Mag and the Garmin EIS no longer connected to the blue wire. The pulses varied in voltage, but the transient voltage readings were mostly in the 5 - 7 volt range. Any suggestions for resolving this issue?
 
I suspect that most EMS' need to have different settings for the different type of tach pulses. Most EI's use a 5V or 12V square wave pulse and mags have something of a different voltage and wave form, as the are watching the P lead. No idea what the magnetic unit uses. I would scour the G3X config for a setting of the pulse type. I am pretty sure I had to set it on the Dynon but just don't remember on the Garmin.

Larry
 
So you should have a wire from terminal #6 on the Emag that goes to pin 8 on the J243 connector on the GEA 24.
I'm guessing this hasn't been connected yet.

EDIT: Heres the Garmin interconnect drawing related to Pmags and RPM, plus some more...
190-01115-01 rev ap
 

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