MGV101 Posted May 13, 2022 Report Share Posted May 13, 2022 Helping a friend diagnose his 1NZ Yaris with a G4X Xtreme. Most problem had been fixed other then the ECU Hold Power function. I think it is missing a diode to initially power up the ECU when the ignition key is on but somehow it would manage to power itself on when the key is in the start position. This is not why I am asking for help here though as I am sure installing diode will fix it. The problem we have is trying to switch off the ECU once it has powered on. Looking at the stock wiring diagrams, seems like the main power relay also provides power to a few other devices including a VSV purge solenoid. Link's diagrams it does specifically show under this situation, Ign/Inj driver must be used but we are using AUX 7 to drive the power relay right now. I guess this is because the solenoid would cause Output Back-feeding keeping the ECU powered on? The ECU Hold Power is currently connected to AUX 7 as the stock relay is actually driven by +12V from the ECU side. I know the injector drivers are ground driven (Low Side Driver) only so they cannot be used so I tried to configure one of the ignition drives given ignition system is positively driven but looking at in the software there is also no option to select Driver type set it to High Side even for the ignition drives. So given the AUX inputs cannot be used due to output back-feeding and the ignition/injector drivers does not given our a high side driven output, I have no idea what output to use. I am out of ideas on how to wire this up and hope I can get some help here. Thank you. Quote Link to comment Share on other sites More sharing options...
MGV101 Posted May 13, 2022 Author Report Share Posted May 13, 2022 Actually, when playing with the the settings and setting the driver type to low side, I've caused to ECU to immediately shit down as it stopped providing power to the main power relay. Somehow the changes got stored without pressing ctrl-S and I had to disconnect the relay wiring from AUX 7 and hook it up directly to the battery to power on the relay and turn on the ECU disconnecting the relay from the battery and the ECU would immediately power it down. So this makes me think maybe this is not Output Back-feed keeping the ECU powered on? Looks like the ECU just refuses to deactivate the output to the relay to power itself down. The DI input for igniton is working fine. I can see its status changing between active and inactive as I turn the ignition on and off. The ECU hold power would show as Active when the ignition is on and Fault when the ignition is off and the ECU is supposed to shut down. Quote Link to comment Share on other sites More sharing options...
Adamw Posted May 13, 2022 Report Share Posted May 13, 2022 Can you sketch a schematic of the power circuits. Quote Link to comment Share on other sites More sharing options...
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