Infinity Lowside outputs | AEM
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Last seen: 3 months 1 week ago
Joined: 11/02/2016 - 14:23
Infinity Lowside outputs

Hi all,

Just wondered if anyone from AEM could explain the operation of the Lowside outputs, as I have a few functional issues.

When the ecu is turned off, do the lowside outputs become a ground or remain open circuit?


I had assumed that lowside outputs would be open circuit when the ecu was turned off, and remain so until activated by whatever strategy the lowside condition is mapped for. 


I have just had a nitrous explosion in my inlet manifold. It appears that when I turned the ecu off, the lowside output controlling the nitrous relay had turned to ground, thus filling the intake system with nitrous and fuel. (single point wet system used). Upon restarting engine had a huge nitrous explosion.

I had assumed the lowside output would be open circuit when ecu was turned off.  If it's meant to be open circuit, what would cause the lowside output to be a ground when ecu was turned off? (I'm using a 708 ecu)


Many thanks,



Last seen: 1 month 2 weeks ago
Joined: 09/14/2014 - 10:21
You should never have

You should never have permanent battery power on the other side of a solenoid - especially something like a nitrous solenoid. It should always be switched 12V powering all your solenoids (and pretty much everything else that needs 12v and is actuated by the EMS for that matter). 


General rule is when the EMS is off, you aren't counting on it to "do" any function. 

Last seen: 2 weeks 1 day ago
Joined: 06/07/2014 - 14:29
I'm very sorry to hear about

I'm very sorry to hear about your nitrous mishap but I agree with the advice above. The ECU will turn the transistor off after the ECU shuts down, you should be able to confirm this behavior for other outputs like fuel pumps or coolant fans or boost control solenoids. But even when the ECU turns that transistor off the flyback diodes present on some LS_Output pins could might result in unexpected behavior if the other side of the solenoid coil has 12V power when the ECU is switched off.  Consider controlling both sides of the nitrous solenoid,  only give it 12V power when the engine RPM is high enough to be safe.