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

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Information Bus: Testing and Inspection

Intelligent Switching Unit Diagnosis

ISU integrates such complex unites and wiring into a micro-controller and also controls itself intelligently.
By doing that, the number of components gets smaller and the wiring simpler, in addition, the diagnostics of electrical easier by using the scan tool.
There is a communication circuit between ISU and the Scan Tool, following items can be serviced.
- Input condition display.
- Actuating the outputs.
- Key coding the transmitter.
- Output condition display (ON/OFF).