Connecting PSU (pc) to amp with lighted switch resulting in failure. Is common ground problem?

Using a desktop psu to power a speaker amp. Have tested and it works fine. I wanted to add a lighted switch. The plan was to attach it to the green-to-ground short that turns on the psu, then attach the "everything's ok" grey wire with it's +5Vdc. This doesn't work, not sure why but it doesn't output the 5 volts I expected. I tested the light with the "standby" purple wire, this proved the light worked at 5 volts and that it was functional. I didn't want the light just 'always on' since there's no point in having it lit then. I tried attaching various 5V red wires and grounds but found that in all combinations the amp's power indicator light and the switch's light would each dim then quickly relight then dim.....repeatedly. I can only assume the light is not using a sufficient amount of power and may be causing a short. Since all black wires and the case are common ground I believe there is no solution to attaching the switch to the psu directly while also lighting it.
The switch is the 3-pronged variety with power  |  load (light)  |  ground
The amp requires a ground, 12 Vdc, and a remote which is actually 12 Vdc also (I have just shorted them and turn the power supply on/off instead as I'm not sure if the amp draws much power when the remote is off/disconnected.

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Andale_The_Great (author) 6 years ago
I've SOLVED it!!

I used the -12 V blue wire to power the light (not sure it is an LED actually). Only downside is I wanted the 5 V because I didn't want it to be quite so bright, but it works.
NachoMahma6 years ago
. Sketch out a schematic of your wiring and see if you can spot the problem.
Andale_The_Great (author)  NachoMahma6 years ago
The diagram:

A video of it actually happening:
. You may have the LED in series with the power/green(on) wire causing a voltage drop. IIRC, that needs to be full 5V.
Andale_The_Great (author)  NachoMahma6 years ago
I've tried to reformat this setup a few times (I didn't draw them all out but you can probably guess the obvious ones) and I can't seem to find a way around this. The problem as I see it is having that green (on) wire connected at the same time as the LED.