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G4 Storm install - Aux outputs grounded before ECU first powered up


TURSTY
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Hi There,

I'm in the process of installing a G4 Storm into a 76 Toyota KE30 with a MRP designed turbo 7AGE 1800 20v. The whole car has been rewired from scratch and we just finished the last of the ECU wiring last night.

While doing a few initial tests of the wiring I have noticed all the AUX output triggers from the ECU are going to ground (I thought these would trigger a relay by providing a ground when the ECU tells them to, but would otherwise be open circuit). The ECU has not yet had power to it (the fuse for the main relay is removed) and is fresh out of the box. Is this normal behaviour until the ECU is powered up and the AUX outputs are configured - i.e. could these be normally closed until set up, or do I need to start looking for a ground loop?

Specific channels that are currently providing a ground (both via continuity tests and volt measurements with a multi meter):

Aux Out 1 - Feed fuel pump relay ground trigger
Aux Out 2 - Lift Fuel pump relay ground trigger
Aux Out 8 - Warning light

I have not had a change to test all the rest of the Aux out's but they may all be closed to ground.

Cheers,
Sam

 

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Yes this is normal expected behavior and will happen on any of the drives that have flyback diodes fitted.  In your case this will be Aux 1-8.  If you use ignition or injector drives as Auxiliaries they wont do this as they are not fitted with flyback diodes.  The 12V supply to those relays must be a switched 12V source as per the diagrams in the help file. 

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Yes this is normal expected behavior and will happen on any of the drives that have flyback diodes fitted.  In your case this will be Aux 1-8.  If you use ignition or injector drives as Auxiliaries they wont do this as they are not fitted with flyback diodes.  The 12V supply to those relays must be a switched 12V source as per the diagrams in the help file. 

Thanks for the quick reply Adam.

Ok cool - So will the AUX out circuits disconnect their ground as soon as the ECU powers up, or will they remain grounded until their configurations are set up initially and the ECU knows to trigger these to ground under certain conditions?

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It will depending on what the map that is loaded into the ecu has assigned to each aux.  Any that arent assigned or that arent activated will jump to open circuit as soon as powered up.  However there will likely be some that are already assigned to functions such as Fuel pump, CE light, etc that may remain grounded on power up.  You wont know which ones until you look at the map that is presently loaded into it.

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It will depending on what the map that is loaded into the ecu has assigned to each aux.  Any that arent assigned or that arent activated will jump to open circuit as soon as powered up.  However there will likely be some that are already assigned to functions such as Fuel pump, CE light, etc that may remain grounded on power up.  You wont know which ones until you look at the map that is presently loaded into

Ok thanks. One last question - so will all the AUX outputs jump to ground once power is removed from the ECU - i.e. key goes off?

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