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)

Or, hide this message: temporarily or permanently

Sensor and Actuator Diagnostic Procedures



Sensor and Actuator Diagnostic Procedures

Operational Signal Checks

These checks are made with the breakout box installed and normally measure a signal voltage or frequency. They are useful for determining an in-range type concern, or an intermittent connection.

In the case of an intermittent concern, monitoring a suspected circuit and recreating the environmental or physical conditions that caused the complaint will help verify if a problem is in a particular circuit.

It is critical when measuring the signal level of a circuit to understand the function and whether it is an analog voltage, digital frequency, sine wave or digital communication signal. A standard digital multimeter has certain limitations in measuring any circuit that has a frequency.

WARNING: RED-STRIPED WIRES CARRY 115 V DC. SEVERE ELECTRICAL SHOCK MAY BE RECEIVED. DO NOT PIERCE.

CAUTION: Do not pierce engine electrical wires or damage to the harness may occur.