How to determine the pin voltage of OBD2 female connector?
To determine whether the power pin voltage of the OBD2 female connector is normal, the main method is to use a multimeter for testing, and auxiliary judgment can also be made by observing the status of related equipment. The following are the specific methods:
Measure with a multimeter
preparation
Ensure that the multimeter functions properly, adjust the multimeter to the DC voltage measurement gear, and the range should be greater than the vehicle power supply voltage. Generally, cars have a 12V system, and a DC voltage range of 20V or higher can be selected; For some large vehicles such as trucks that may have a 24V system, choose the appropriate range accordingly.
Find the OBD2 interface of the vehicle, usually located under the driver's seat or near the dashboard, and some models may be located on the side of the center console or other positions.
Identify power pins
Refer to the vehicle's technical manual or relevant information on the OBD2 interface to determine the position of the power pin in the OBD2 female connector. Generally speaking, the 16th pin of the OBD2 interface is the power pin, and the 4th and 5th pins are the ground pins, but there may be differences among different vehicle models.
measure voltage
Insert the red probe of the multimeter into the power pin of the OBD2 interface and the black probe into the ground pin. If the grounding pin is uncertain, the black probe can also be connected to a reliable grounding point such as the metal body of the vehicle, but ensure good contact.
Turn on the ignition switch of the vehicle, but do not start the engine. At this time, the multimeter should display the battery voltage of the vehicle, which is generally normal between 12V and 14V.
Observe the status of relevant equipment
OBD device display: If connected to OBD diagnostic devices or on-board computers or other devices related to the OBD2 interface, the display information of the device can indirectly determine whether the power pin voltage is normal. If the device displays an alarm message indicating low or high voltage, or if the device is working abnormally or restarting frequently, it may be due to a problem with the power pin voltage.
Vehicle electrical system performance: Observe whether other electrical equipment of the vehicle, such as headlights, radio, dashboard backlight, etc., are working properly. If these devices have abnormal brightness, flicker, or malfunction, in addition to checking the equipment itself, it may also be due to abnormal voltage of the power pin of the OBD2 female connector causing problems in the entire vehicle electrical system.
