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)

Or, hide this message: temporarily or permanently

Main Relay (Computer/Fuel System): Description and Operation

The Main Relay (also referred to as Fuel Injection or EGI Relay), located in the right front corner of the engine compartment near the battery, supplies power to the PCM and a number of PCM controlled devices when the ignition is switched "ON", including the circuit opening relay, fuel injectors and a variety of solenoid valves.

The PCM energizes these devices when needed by completing the circuit to ground.