How do you test the PIP signal coming from a EDIS unit?

Idealy an oscilloscope would be used for this, but you may be able to use an LED and series resistor to check for activity on the PIP line.

There will be a pulse on the PIP line twice per crank revolution (for a 4 cylinder application), so the LED should visibly flash during cranking (when the engine is actualy running it would be flashing too quickly to see).

If you try this use a fairly high value resistor to avoid loading the PIP line too much. Somewhere around 3-4k should give adequate brightness just for testing with an efficient LED.