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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Quick Test Description


The MCU is able to diagnose a malfunction in the system through the use of a self-test program built into the MCU module. When initiated, the self-test simulates a variety of engine operating conditions in order to detect malfunctions. A malfunction in the system will cause a series of pulsing voltage outputs to be sent to the test equipment. These voltage pulses represent a Service Code which stands for a two-digit number, indicating a specific problem in the system.
For testing purposes, either the Rotunda Self-Test Automatic Readout (STAR) model No. 07-0004 or equivalent, or a scale type voltmeter may be used.