I never got any Emails.
If we're still talking about the CSD oil pressure switch, then no resistor is needed. You're looking for a intermittent ground on the signal wire from the switch to the light in the cockpit. Everything is checked in reference to ground (meaning one meter lead is connected to frame or some verified grounded piece of metal).
We're talking "one" wire here. The signal wire..... it's touching or close to touching some piece of metal that provides a ground path.
As stated before, you use a megger to find these problems. You disconnect the pressure switch and either hook up at it or the other end of the wire (at the overhead panel). Connect the other megger lead to aircraft ground. Try 250 volts, 500 volts, or higher. You want to see the meter indicate damn near infinity. If it is half scale (10Meg - I'm just throwing that out), you've got high resistance to ground on that wire. "That" is what is causing the light to flicker.
Start disconnecting intermediate plugs to isolate it. Start shaking wire bundles while someone is looking at megger. If it jumps (up or down) that's the problem area. Open up the bundle. Start physically looking at the wire length.
Check the plug pins at the CSD.
That wire "is" your problem. Find out where it's shorted!!!!
As to your other question about running the engine to make the switch????? Just jumper the plug to simulate that..... but that "will" put a ground on the suspect wire. You don't want or need to do that.
There is a piece of test equipment called a TDR. If you're shorted, it''ll tell you the distance from where you're hooked into the wire.
Almost all warning lights Boeing, Douglas, Airbus, Gulfsteam.... have power on one end of the bulb filament at all times. It is the provided ground on the other side of the filament that turns it on. You are picking up a ground on the signal wire going to the CSD.
