Explanation and Precaution Related to Harness Checking

EXPLANATION AND PRECAUTION RELATED TO HARNESS CHECKING





- Connector symbols are described as seen from the terminal end for the connector.
- The abbreviation "B+" used for the normal judgment value when checking the voltage is the abbreviation for battery positive voltage.





- Be sure to use the special tool (test harness) when, for a waterproof connector, checking while the circuit is conductive. If probe is inserted from the harness side, the waterproof capability will be lowered, thereby causing/corrosion, so never do so.
- When a connector is disconnected in order to check terminal voltage, etc., never insert a probe if the terminal to be checked is a female pin, because the forceful insertion of a probe will cause improper or incomplete contact.





- Also, if there is no test harness that conforms to the connector, use the test harness set (MB991348) which can be directly connected between the terminals.
- When disconnecting the connector and inspecting the terminal voltage, etc., if the inspection terminal is a female pin, the special tool (inspection harness set: MB991223) should be used instead of inserting a probe.





- When checking for damaged or disconnected wiring of a harness (open circuit) and if both ends of the harness are unconnected, use a jumper wire to ground one end of the harness, and then check for continuity between the other end and ground. By doing this, you can check for damaged or disconnected wiring, and, if there is no continuity, the harness should be repaired.
However, when checking for a open circuit in the power supply line, check for continuity between both ends directly, without using a jumper wire to ground one end of the harness.





- When checking for a harness short-circuit (short-circuit to ground), open one end of the harness and then check for continuity between the other end and ground. If there is continuity, the harness is short-circuited to ground and should be repaired.





- If the voltage (power-supply voltage) supplied to a sensor is not normal, repair the harness. If the voltage to the sensor is still not normal after the harness has been repaired, replace the engine control module and check again.