Ground at the fuse box located in the engine compartment.

1996 Mitsubishi montero 3.0L 12 valves.......I qot a question....Does the fuse box has to be grounded or joint together with the cable that goes to the negative side of the battery..??.....Does anyone have a diagram or layout of this particular fuse box...??......

Your test light can find a ground through an unpowered fuse if that's what you mean. If you're using an led test light that's high resistance and consumes only like 7 miliamps, it may light up by finding a ground through the computer.

Thank you so much for the information.....I appreciated it.....I have a question....In the engine compartment, there is a frame that houses the relays and the fuses....Does this metal frame has to be attached together with the cable that goes to the negative side of the battery..??....I ask because i disconnect this cable from the vehicle chassis because i can not reach the battery pole to connect it.....I do not know if i explain myself very clear.....

If the metal frame has cables bolted to it then it's a ground point. Can you take a photo?

The metal frame (housing all the relays and fuses in the engine compartment) was bolted to the vehicle chassis along with the battery negative cable.....I unbolted it because i could not reach the battery pole.....I can not remember if after i did this action the vehicle failed to start (no spark).....Right now there are two relays that are not working and two fuses (10 amps each) that have no current.....I will take a picture as soon as i can .....and i will look for a battery that has the poles in the opposite side so i can reach it with the cable...

Relay can be ground side or power side controlled, and also they can switch the load circuit on the power side or on the ground side.

Generally I would think a relay mounted on a fuse box is much more likely to switch the power side of a circuit but relay coil itself controlled by a pull down.