Most common. All OBD1 vehicles have a DLC1 located in the engine compartment. Works with DLC1 17 & 22 pin.

Some vehicles also have a DLC2 located in the passenger compartment. Most vehicles with a DLC2 require connecting TE2 to E1 on the DLC2 to read the serial data stream from the DLC1.

For use inside the passenger compartment on vehicles equipped with DLC2. Use requires adding positive terminal to Opt B position of DLC2. Wire with terminal attached included.

Does not have the ability to read DLC voltages (oxygen sensors, fuel pump, EFI circuit) because the DLC2 doesn't have the needed terminals.

For using OBD1-DLC1 inside the passenger compartment on vehicles equipped with DLC2. Use requires adding positive terminal to Opt B position of DLC2. Wire with terminal attached included.

Does not have the ability to read DLC voltages (oxygen sensors, fuel pump, EFI circuit) because the DLC2 doesn't have the needed terminals.

The DLC1 ends are from salvaged vehicles because there isn't a manufacturer that produces them. The DLC2 end and cable are custom fabricated to include the needed wires.