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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Shift Point Signal

A Shift Point Signal is also connected to the Motronic control module, the signal is directional IN only (PIN 18 - INPUT ONLY).

The shift point signal comes from the automatic transmission control module (TCM). The Motronic control module uses this signal to recognize upshifts and downshifts of the automatic transmission.

For additional shifting comfort, The Motronic control module retards the ignition timing and therefore reduces engine torque during shift operations.

Self-diagnosis:

^ Self-diagnosis (OBD) recognizes a continuous signal (short to ground) as a fault. The signal is then no longer accepted.