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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Coolant Temperature Sensor/Switch (For Computer): Description and Operation

PURPOSE
By measuring the amount of resistance at the sensor, the Engine Control Module (ECM) can adjust the length of injector opening time required by the engine.

OPERATION
As water temperature increases, sensor resistance decreases. The ECM receives sensor information as resistance to ground. Water temperature information is used to determine proper fuel delivery.