How to test Lonsdor K518 OBD or DB25 Adapter?

How to test Lonsdor K518 OBD or DB25 Adapter?
When Lonsdor K518ISE/K518S cannot connect with any supported car models, you must test the OBD or DB25 adapter.
Is it more likely because of the OBD cable, or less likely because of the device?

Lonsdor OBD-BD25 test cable test:
Step 1: Unplug the K518ISE host and shut it down
Step 2: Connect the DB25 line (OBD line) to the k518ISE host, and use a multimeter to switch to the diode position
Note that there are 3 connectors on the OBD cable:
Connector 1: Connect to K518ISE OBD port;
Connector 2: Connect KPROG Adapter
Connector 3: Connect to the vehicle OBD port

Figure 1: The 3 connectors on the OBD cable

Step 3: Click on the metal part with a red pen (as shown in the red part in Figure 2)

Figure 2: K518ISE OBD port metal part

Step 4: Use a black pen to test the resistance of each pin of the car connector (as shown in Figure 3), and ensure that the holding method of the car connector is as shown in the figure:

PIN 1 and 8 should have no resistors; PIN2,3,4,5,6,7,9,10,11,12,13,14,15,16 should have resistors.
If there is no resistance, there is a problem with the DB25 line; if everything is normal, but the model (model that supports K518ISE) still cannot be connected, you need to send the DB25 line and the host back to Lonsdor for inspection (if yes, please contact your dealer).