Aux Output Supplement

Aux Output Supplement

Emtron ECU systems have a high number auxiliary outputs on all products offered in addition to being able to utilize unused fuel and ignition channels as additional outputs.  These extra outputs can be used for various functions such as solenoid control, relay control (fans, fuel pumps, etc), PWM systems, and more.  Keeping with the concept of Emtron flexibility, the Aux Outputs match these needs.  

Regardless of this added flexibility, careful planning for best output use is still necessary.  

Aux Output Connections

SL Series ECU – 10 Aux Outputs

Auxiliary 1-4: Low side

    Outputs rest at 0V when ECU is powered off

Outputs are open when not being commanded on

        Low side control of relays, solenoids, lights, etc

Auxiliary 5-8: High side/Low side

    Outputs rest at 0V when ECU is powered off

    Outputs are open when not being commanded on regardless of polarity

        Low side or high side control of relays, solenoids, lights, etc 

Auxiliary 9-10: Half bridge (DC motor control – DBW)

    Outputs rest at 0V when ECU is off 

    Outputs command the opposite polarity when off

        IE – High side output as commanded on is low side when off

KV Series ECU – 16 Aux Outputs

Auxiliary 1-8: High side/Low side

Outputs rest at 0V when ECU is powered off

    Outputs are open when not being commanded on/off regardless of polarity

        Low side or high side control of relays, solenoids, lights, etc 

Auxiliary 9-16: Half bridge (DC motor control – DBW – Aux 9-12 KV8 ONLY)

Outputs rest at 0V when ECU is off 

    Outputs command the opposite polarity when off

                IE – High side output as commanded on is low side when off

** KV8 Aux 13-16 cannot be used as DBW control, but the functionality regarding output state is the same

Common Issues 

When using an Aux Output to control a low side output that is connected to constant power.  

The result is the output is ON when the ECU is powered off.

See KV Series Hardware Manual - Section 3.6

This is why the control side of many systems (relays, solenoids, etc) is switched on with ignition supply (OEM).  

Due to the flexibility of the output, controlling the system as High Side instead can resolve this issue. 

When using a Half Bridge output on a circuit that is sensitive to reverse polarity, this can create issues with actuation if that particular output is expecting an open circuit when commanded off.  

** For output specifications (frequency, PWM, current ratings), see ECU specification sheets.