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)

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Valve Block







Valve Block
The Electronic Control Unit (ECU) receives + 12 V on pin 3.
- This also provides current to the valves on the valve block, pins 1 and 10.

The valves are grounded, if necessary, through the valve block by a Pulse Width Modulation (PWM) signal.

The frequency depends on how long the valves are activated.