20
6 Cylinder Dual Power Buss*
Switches and Breakers recommendations, Dual ECU
*Dual Power Buss means that normally both busses are powered on all the time and both ECU’s are
running all the time when the engine is running. Both Busses each have their own alternator and battery.
Power Buss A powers the Primary ECU & injectors 1,2,3 and Power Buss B powers the Backup ECU &
injectors 4,5,6. Each Buss powers an ignition coil pack on systems doing ignition control. The Injector
Relay Switch can redirect injector +12V power to either power bus when the switch is in PRI or BAK
positions and also redirect all 6 injector signals to either the PRI or BAK ecu. Dual Buss design is an
option when the airplane has dual high amperage alternators. If your 2
nd
alternator is lower amperage
emergency backup type do not choose the Dual Buss method.
*** If Dual ECU using older round 3-1/8” programmer, add 1 more switch for ecu select, and if LOP
operation will be used, add 1 more switch again to arrive at a total of 9 switches. Add 1 more 2A breaker
for Fault LED for a total of 19 Breakers.
The more modern Design1 6.25” wide programmer has its own ECU Pri/Bak select key and a LOP key
on its keypad.
Several items above do not need switches, but can just turn on with the Main Buss power
switch/contactor.
Some of the above options may not be needed such as the Octane Switch or Closed Loop switch so this
will change the total number of switches required. Fuel pumps and ignition coils need dedicated switches
to allow for individual function testing or “mag check”
Item Breakers
Quantity
Breaker
Amps
Switches
Quantity
Switch
included in
system
Fuel Pumps 2 15 2, SPST No
ECUs 2 2 Optional, SPST No
Ignition Coils 2 15 2, SPST No
Injectors 6 5 None No
Injector power Bus A 1 15 None No
Injector power Bus B 1 15 None No
Injector Relay 6cyl &
Knob Relay
2 2
1, DPDT On-Off-On
(Center Off)
Yes
Wideband Controller 1 5
None. Relay control
through Pin 1 on 16
pin Molex
Not needed
Octane Select 0
None, switches ecu
input to ground.
1, SPST. Pin 10 on 16
pin Molex, switch to
ground.
No
SDS Card Logger 1 2 No Not needed
Closed Loop Quick
Enable/ Disable
Switch
0
None, switches ecu
input to ground.
1, SPST, Pin 9 on 16
pin Molex, switch to
ground.
No
Totals for
6cyl Single
bus.
18
Breakers
Total.
7 Switches
Total ***.
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