Im trying to hook up a lighted trailer hitch cover

There are several potential reasons why the trailer lights on a 1998 Mitsubishi Montero might not be working:

1. Blown Fuse: Check the fuse panel for a blown fuse related to the trailer lights. Replace the fuse if it is blown.
2. Wiring issue: Inspect the trailer light wiring for any signs of damage or corrosion. If there is damage, repair or replace the wiring.
3. Bad Ground: Make sure that the trailer lights have a good ground connection. Test the ground connection to ensure it's making a good electrical connection.
4. Faulty Light Bulbs: Check the trailer light bulbs to see if they are burned out. Replace any damaged or burned-out bulbs.
5. Trailer Light Connector: The problem could be with the trailer light connector. Check the connector for any signs of damage or corrosion. Clean the connector or replace it if needed.

If you are unable to resolve the issue, it may be necessary to take your vehicle to a qualified mechanic for further inspection and repair.

Some people wire trailer plugs differently. If the plug is not wired differently than yours, make sure the tow ball is clean. No rust. That's where the trailer gets its ground from. Usually they will work if thats the case, but not right. I can't remember what the wire colors are right now. Go to etrailer and look up the diagram.

check the wiring near the trailer hitch for breaks shorts and places where the wires enter/leave any metal channels where the wires arent in a plastic cover(available at parts stores)sometimes the installers will not cover the wires and they get pinched or wear through causing a short..once repaired, put the wire in a protective cover and tape the ends so it wont move..repost with findings please...

The harnes u buy for the van should plug right in and it is located i think inside the left hand rear wheel wall carpet. Hope this helps.

On trailer plug, white is ground,yellow is left turn signal,green is right turn signal & brown is tailights.

Sometime around 2000, GM started putting trailering pre-wire harnesses in the vehicle. Your truck may have this harness built in and would greatly simplify brake controller installation. Look under the glovebox and see if there is a wire harness tied off. There will be four wires in this harness, which should be run over to the steering column to use it. Most trailer brake controllers are compatible with this harness.
The four wires in the harness are: Red, 12vdc; black, ground; blue or purple, brake pedal; and brown or white, trailer brake wire to seven pin, four pin, or five pin connector at trailer hitch, if your truck came from the factory with a trailer hitch.
If you are adding the hitch and do not have the four wire harness, the under hood wires from your brake controller are Red, connect to one of the studs under the distribution box cover (the distribution box is on the driver's side against the firewall. Underneath the cover are two large threaded studs which are hot from the battery all the time); and the other wire from your brake controller would have to be run the length of the truck along the frame, tied off in several places, to the trailer hitch connector on the bumper. Follow the directions that came with trailer hitch wiring connector to connect this wire to the proper pin in the connector.
If this has helped you, great, and please remember to vote/comment.
Good luck!

Check the bulbs in the trailer. If you know someone with a trailer that you could hook up to try that too. A large majority of trailer lighting systems use a simple circuit pattern. Like Christmas lights. . . one goes out they all go out. etc. Some boat trailer lights will burn out if they are hooked up when it's backed into the water. The pain of trailer stuff is figuring out if its really the trailer or not. When the cover is off the lights make sure you take a good look at the guts of the light. The brass pathways will actually arc and melt. Ruining the light. If its not the trailer start checking the vehicle connections. Remember not to overthink things and start with simple stuff first. Oh and recruit a helper to push the brakes and run back and forth it will speed things up greatly.

you may or may not have a trailering wire harness. look for an extra set of wires underneath the middle of the rear bumper (have a peek around the spare, too). this should have a flat plug on it that looks like it belongs on a videogame controller plug. some models also have a covered socket you should look for. if there doesn't appear to be one, you may have to have a professional or a knowledgeable friend put one in.

if you go to a hitch shop they usually have a plug that fit to stock harness for a price but its easier and safer

tail lights and brake lights, if u had factory wiring then it will be marked trailer tow fuse.