This the possibly ignorant part of me rising to the top...
I have seen CEL plugs like GekoXL7 described on pre OBDII (before 1996) Sidekicks/Vitaras. In order to get the fault code to flash on the CEL display, you short the pins as described above. The CEL will flash a in a pattern that can be decoded with the appropriate CEL Decode table (which I don't have...) to indicate what circuit/component/system is causing the fault condition.
In the US, every passenger vehicle manufactured after 1996 was required to be equipped with an OBDII system that allowed the owner/service person to read the fault codes provided by the ECU.
I had a 2002 GV (Tracker) with th5 2.5 V6 that had an OBDII port.
Usually this port is located under the dashboard in a semi-convenient place. In the US (where we apparently drive on the wrong side
) the port is located on the left side near the steering wheel. One borrows a reader from the local factors/auto parts store (here in the US, it's a promotions gimmick to sell parts) or buy one to read the fault code - which can be found by Googling OBDII fault codes on the Interwebs.I hope that this helps!