If you've got a PBP2.6 manual I recollect there are hard numbers in it for isolation resistance. I thought the desired value from the old manual was several hundred kohms but I don't see it in the PBP3 manual.

If you look here http://ww1.microchip.com/downloads/e...es/_91017b.pdf it says 1kohm isn't enough. I have found an LED to ground on the PGC or PGD pins, even with current limit resistor, causes problems. I also remember that a capacitor on the MCLR pin caused a problem.

Just FYI, all these recollections may not be relevant to what you're designing. From experience I now use a switch to disconnect the PGC/PGD and depending on use the MCLR pin from the circuit for ICSP. You can get surface mount components that are very tiny.