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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Engine Speed Sensor: Description and Operation
The
engine speed signal is produced by the seven terminal HEI module in the distributor. The ECM receives pulses from the distributor and the time between these pulses is used to determine engine speed. The ECM adds spark advance modifications to the signal and relays this signal back to the distributor.