Mooney M20E ground for G2

[MMsuper21]

Thanks in advance.

Upgrading the GEM 602 to a G2. Since the shops are backed up for a few months I would like to just install the G2 with the existing probes.Replacing probes and FF when my shop has time. I checked there is enough wiring left to reach the shorter G2  thanks MS for the heads up.

The instruction manual mentioned that if the GEM 602 was grounded to the engine it is critical to be grounded to the airframe otherwise they will void warranty. 

1. How do I tell what the original is grounded to the airframe or engine?

2. I see some cables being ground to the instrument panel frame. (Forgot who mentioned it but said that the panel is grounded to frame and engine) 

3. Where do I run the ground to the airframe.

Looking at the electrical system diagram is see the grounds but not what they are ground to. 

 

IMG_0476.HEIC

[Yetti]

Well first off the Engine is hung with 4 rubber mounts.   there should be a ground strap from engine to firewall on the co pilot side.   Some panels are mounted with rubber mounts.   There is a square stiffener that could be threaded where the Com relay is on the copilot side above the intake vent.    If you have Com Access panels still this will make it easier.   There are also cromoly tubes behind the panel.   If your battery is in the back it is probably grounded to the aluminum skin.

[MMsuper21]

So the aluminum would be considered airframe and could be used for ground? 

[Yetti]

8 hours ago, MMsuper21 said:

So the aluminum would be considered airframe and could be used for ground? 

correct

[Yetti]

but you do want to make sure the ground strap to the engine is in place and the connections are shiny for everything to work properly

[carusoam]

Grounding properly is important for all sensitive electronics…

The statement given for the engine monitor is just obvious, not special…

The last thing they want is your engine accidentally grounding through your monitor… 

 

So… know where your ground straps are… engine, airframe, instrument panel…

PP thoughts only, not an instrument guy…

Best regards,

-a- 

[MMsuper21]

JPI wants their instruments grounded to the engine. So did the old GEM 602.
 

But the G series is to the airframe hence not a plug and play. 

 

 

[N201MKTurbo]

There can be a significant potential difference between the engine and airframe while starting the engine. If the instrument was grounded to the engine, this potential would appear on any data lines connected to other devices. This could potentially (Pun intended) cause a problem.