EMU502 unable to Aux On. To check and re ~~~~~ EMU502 unable to Aux On. To check and re    Emu 502 able to Local on and able to Aux on.Checked EMU 502 battery banks and battery voltage ok.Conducted APS power /no power test ,result ok.Checked and cleaned both M2 electrical coupler head,no sign o oxidation or burn marks-ok.Checked Aux on line of M2 to M2 electrical coupler head cont.check from junction box line 66 (0 ohm) result ok.Checked voltage drop across AXCB,6606 TO 6602no voltage drop,result ok.Carried out cont.check 6603 to 6604 between Aux on & Aux Off push button result ok.Carried out to cont check 6604 to 30 and 6604 to 33 ,result ok.Checked the wire termination of Aux O  push button contact blocks.Found multiple 6602 wires loose.Tightened and security check ok.Checked Aux on push button contact block wire termination,securiy check ok.Carried out function test of #3502 Aux on and off push buttom ok. Checked by Koh/Jack/Zul/Joshua. 12/05/21