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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Control-Module Test (Functional Descriptions)




Control Unit Self-Test

The program and variable memories of the engine control unit are checked regularly. If a fault occurs a defect code is stored in the defect code memory.

Other components are also checked. The resulting fault code entries, however, may also be attributed to other faults or problems. For this reason further information is evaluated in test mode in order to determine whether the problem relay is a control unit fault.