no its not rubber. its hard plastic.
here are some clearer pics.
the green line follows the wiring as it comes in through the guard and goes via the plug, directly into the top of the 'puck'.
there are no other wires coming in our out of the 'puck'.
the dotted line shows where it turns inside the guard, and heads rear-wards. i can follow it under the guard for about 200mm, before its hidden behind the inner guard.
the plug looks like the standard nissan plug, ie same type as the boost solenoid, so i thought it was something standard.