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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Power Steering Pressure Switch: Description and Operation

PURPOSE
The Power Steering Pressure (PSP) Switch signals the Engine Control Module (ECM) when the steering wheel is turned.

OPERATION
When the steering wheel is moved at idle speed, the PSP switch closes, sending a ground signal to the fuel ECM. On receiving this signal, the ECM increases idle speed to compensate for the additional load from the power steering pump.