An odd problem with Auxiliary Output 6.

[James Wingfield]

I'm seeing ann odd problem when using Auxiliary Output 6 on my LEM G3 ECU. I've got other outputs wired up without any problems but when trying to drive my fuel pump relay from output6 it seems to fail for some reason. I already have another relay set up to drive my engine fans and that works fine so I tried switching components from one system to the other as a means of identifying where the problem's coming from and found that it seemed to be the ECU output that was the common factor. When I try using output3 (my Engine Fan control) to drive the FP relay it all works as expected, but if I use Output6 to drive the engine fans they no longer work properly. Likewise, if I switch the actual relays then the problem always sticks with output6 and not the relay itself. So what actually happens is as follows: I turn on the ignition and the relay gets grounded through the ECU as required. The relay then activates and turns on the fuel pump. The engine runs fine like this but when I turn off the engine (i.e. ignition off) my fuel pump continue to run. If I then switch on the ignition, the pump turns off. Apparently the relay function gets reversed for some reasson?! It stays like this until I remove one of the relay terminals (on the low power side) which then breaks the circuit and turns off the pump. If I now reconnect the relay terminal, the pumps stay off and everything appears to be functioning correctly again. I'm not sure what could be causing this but is there a common issue with Aux6 on these? Thanks, James

[Guest Dave]

you need to make sure that the power supply to the relay coil is feed from an ignition key source if it is 12volt from batt then the ecu will be staying semi powered up

 

Regards

David Heerdegen

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