915Is ECU ISSUE

Interesting.

Any comments on turning the key to the ACC position prior to the start sequence.  The Montaer tech said that it energizes the ECU.  Seems strange to me.

Hi Gene

I can only guess.  It would appear they are using the ACC position to feed the battery power to the system for initial start. (via a relay normally)  Most OEM will use a non latching toggle to do that function.  

Cheers

Gene,
Initially I was thinking that the Montaer start power scheme provides start power from the key switch in the ACC and START positions, and removes start power once the key is released to the RUN position. This would allow the operator to energize the lanes and get fuel pressure in the ACC position, then maintain it through the start cycle. However, as you move the key from ACC to START, you must pass through the RUN position. So if this was all done with a simple 4-position mechanical switch, the pass through the run position would drop out start power and throw the lanes into fault/reset. So there must be a little more to it. Possibly a latching relay (as RW suggests) that is initialized in the ACC position, and holds start power on until either the engine is running or the key is moved to the OFF position. If you have a wiring diagram for the aircraft and can post it, we can probably tell you how it works. I would have thought that this would be well described in the Montaer Operating Manual.  

It is not.  The Montaer tech chastised me for not doing it and it is not in the POH. Never needed to do it before and I have flown the aircraft 53 hours since I got it on October 1st.  Here is the what POH says.  Never mentions the ACC.

Hi Gene

The order of the checklist makes me think that activating your backup alternator may also engage START POWER to the ECU.  I can’t think of any other reason they would want the backup alternator engaged during startup. In the order of things, they have you turn it on right before turning the lanes on, and off right after the engine starts, pretty much like a START POWER switch would operate. 

Assuming they are using the backup alternator to power both the engine and airframe functions in the event alternator A and B both fail, then activating the backup alternator also ties the airframe electrical and engine electrical systems together, which is essentially what a start power switches does. You could experiment with that:  Specifically, leave the ignition switch in Off or Run (try both), turn on the Master Switch, the Alt switch, then the Lane Switches and see if the lane lights come on and then go off. If they do, the ACC position is irrelevant. 

The attitude of your Montaer Tech makes me think he does not know how it works, if he did he would have explained it to you clearly.  I would try to get my hands on a complete wiring diagram. Fully understanding the aircraft makes flying it safer. 

Lastly, does your aircraft have a 12V or 24V electrical system?  There are some differences in the two regarding the Start Power and Backup Power systems.