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

General System Description

Engine fuel, ignition, charging and emissions systems are controlled by the Programmed Fuel Injection Control System (PGM-FI). An array of underhood sensors continually report all aspects of engine operation to the PGM electronic control unit (ECU). The ECU uses the information it receives to adjust the output devices connected to it to improve driveability and fuel economy. If a sensor is perceived by the ECU to be providing inaccurate data, it reverts operation to a preset back-up program to allow the vehicle to operate until repairs can be made. When such a problem occurs, the ECU illuminates the Check Engine light on the dashboard to alert the driver that a fault has occurred and that the vehicle requires service.