Operation CHARM: Car repair manuals for everyone.
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

(Some people have issue connecting. LEMON is investigating. For now, use Firefox or change your DNS server)

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Knock Sensor: Testing and Inspection

Results ot Faulty Knock Sensor (KS) Operation
Loss of the KS signal or loss of ground at the KS module would cause the signal to the powertrain control module (PCM) to remain high. This condition would cause the PCM to control the ignition control (IC) as if no detonation were occurring. No retarding by the KS system would occur, and detonation could become severe under heavy engine load conditions.