2000 Accord knock sensor troubleshooting

I'm trying to test the knock sensor on a 2000 Accord 4 cylinder. The
Haynes service manual procedure involves draining the engine oil
removing the sensor and measuring the AC voltage generated by the
sensor by lightly tapping it with a hammer. This sensor is basically a
microphone. Why would it have to be removed from the engine block to
perform this test ? I would think that tapping the block where its
mounted should generate a reasonable test signal.

 

agreed.

the advantage of removal however is that if there's a bad mechanical
connection, which i guess is possible, you'll remake it on
reinstallation, and hopefully make sure it's good. it also depends on
the sensor head's physical connection point. if it's screwed through
the block to touch the wet liner, the outside tapping thing may not be
that effective.

last thing: haynes recommend tapping the sensor directly with a hammer?
geeze, those people need their heads tapping with a hammer. if ever i
needed reminding why haynes manuals are to be avoided...