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Does anyone know how the ecu hold power works on M1 platform? If the batery ( +) inputs to ecu are driven through a ecu hold power controlled relay, how does the ecu recive power?
How is the baterry backup pin connected? Is it actually used on M1? Should this be a switched battery (+) through another relay or ignition switch?
The info is quite vague in help file
Its pretty straight forward and if done incorrectly will yield in loss of inputted data at every key cycle and all kinds of other weird shit.
ecu receives permanent power from the battery. ecu sees key switch as a input as well. ecu triggers your wired main relay which is independently powered by the battery. the main relay powers the ecu and this is what is actually drawing the power from and relying on for all operations.
Its actually how just about every automotive ecu works.
I don't think the response is applicable to the M1 series ECUs. From my research the M1 Battery Backup pin is not yet used in most firmware and the ECU does not use volatile memory.
Wanted to share my research in case others are looking for information specific to the M1 ECUs.
Additional consideration for those potentially running a John Reed Racing firmware package... he has a video using one of the CAN keypads that recommends wiring the battery backup in order to have the ECU retain the button's last value (button has a flash backed configuration).