UK-POLOS.NET - THE VW Polo Forum

I’ve recently installed a new headunit into the polo, when connected to the standard iso connectors on the car the headunit has power from the constant live, but as soon as the ignition is turned on all power is lost.

I’ve tried an adapter and switching the red/yellow wires around but this hasn’t resolved the issue.

Any help is appreciated

Do you mean power is lost when the ignition is switched on? Or when switched off and then on again? The unit forgets all presets/settings?
Yeah switching the red and yellow wire would usually fix that problem, maybe someone messed with the wiring in the past. Best thing to do is get a multimeter and figure out which is the constant + and the switched +