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Weird (for me) behavior from 12v Aux Output


MaxouGT4
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Hi,

I have a my fuel pump relay (30 amps) that received a 12v signal from my TST205+ on Aux Output 7 (original fuel pump signal but not on ground anymore). If I test the voltage when the car is at "On"/not running and without relay I read 11.75V. If I back prob the terminal of the relay when the relay is plug I get 0.5V. If i remove the terminal from the ecu and try a direct 12.6V it works.

Is it a normal behavior? I guess I could just change my signal to be a ground again a give my 86 pin of a my relay a 12v with a 2amps fuse but I'm wondering if it's normal.

I've check the ground for the ecu and relay and I don't have any resistance.

And what is the difference between  Aux Output and Ign Output anyway?

Thank you!

TST205 capture.JPG

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The aux outputs in most of our plug-ins are low side drive only - this means they switch to ground.  They are "pulled up" to regulated 12V when off but that is generally not enough to switch a device on that requires a 12V signal.  

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This what I thought! I wasn't sure. And if i understand correctly, the Ignition outputs should be battery/alternator voltage correct or it's again regulated?

 

I will switch back to ground. Thank you!

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