If you want to physically trace the two-wire path from Knock Sensor to Ignition Control Unit (ICU), here goes:

There is a Black and a Green wire. From the Knock Sensor, they go to an 8-pin connector back in the left rear corner of the engine compartment (maybe tie-wrapped up under the strut tower support). The Black wire goes thru Conn. Pin 7, the Green thru Pin 6.

From there they go to the ICU (inside, behind panel next to driver's left leg). The Black wire comes in to ICU Pin 12, the Green to Pin 13.

Try opening each connection and using the recommended cleaning procedures. Sometimes just disconnecting the reconnecting the junctions cures an intermittent failure.
--
Bruce Young,
'93 940-NA (current)
'80 GLE V8 (Now gone)
'83 Turbo 245
'73 142 (98K)
'71 144 (track modified--and still here)
New 144 from '67 to '78
Used '62 122 from '63 to '67