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)
Or, hide this message:
temporarily or
permanently
Voltage Signal: Description and Operation
The ECM receives engine speed (RPM) information from
ignition coil references pulses. This is one of the input signals required for the ECM to make air/fuel ratio adjustments. It is also factored in when the ECM calculates other input and output data.