I have a 96 ranger. I plugged it into a boat trailer oe tail light on the boat trailer was out I put in a new bulb and the lights flickered on trailer and went out. Now I have no power to the plug on the truck. Truck tail lights brake lights and turn signals work fine just no power to the plug. Have checked all fuses in fuse panel inside truck cab. Can anyone tell me if there is a fuse or a relay or any ideas?

check connections in plug and car
check how the wire is connected to the bulb holders

There is a tail lights fuse for the truck, but not for the trailer.
First, check that your left tail light on the truck is working, if not fix the problem (new bulb, bad contact, fuse).
Then the obvious suggestions regarding the trailer are: Check the tail light portion of the bulb to be sure it is not blown. If good (best to put in new one to be sure), then check the wiring from the front of the trailer all of the way to the non working bulb, including every connection and at any place it is secured to the trailer frame. If all is good with the trailer circuit and bulb, then check the truck's trailer connector, including any adapters. If by chance the truck is wired with a flat 4 wire harness the problem may be solved (but usually the blinkers are the problem). Modern trucks require a 5 wire harness which self adapts to the standard 4 wire trailer circuit. Check for dc power (12 volts) from the truck's female connector. One wire will be ground, others will be taillights (turn on headlights), brake lights (have someone press brake pedal), and blinkers (turn on switch and blinkers).

Possibly the person that borrowed your trailer changed some of the wires. Old-type bulbs don't care about polarity, but LEDs do.

Check your grounds, expecially on the trailer. Check your trailer lights. Do you have some kind of bulbs that are of a high wattage? They may be draining more power than what the motor home is producing. Are there a lot of trailer lights? That could be the drain. If possible, pull out all the trailer bulbs and insert one at a time while watching for the lights to be affected.

Have you checked the bulbs? Some people don't beleive all the lights can burn out at once but when one brake light is on they are all on and for the same amount of time.
If the bulbs are fine then check the connection where the trailer plug is to the main harness. Some of those connectors go between the main harness and the tail lights and the connector can go bad.

Use the white wire also,the ground on the trailer is not getting ground from the vehicle,so use the white wire to ground to the truck,and the white wire to the ground on the trailer,if this was helpful,at all,please rate,thank you.

sounds like wireing is shorted together. you need to trace down wires and check for bad spots in wireing. also be sure and check plug if you are set up for trailer lights.

If you happen to have a trailer wiring adapter plugged into the harness, remove it first and see if they start working. I've more than one of those mess up the rear lights. If you have the three-bulb tail lights, use a test light to see if there is power to the tail bulb sockets. If there isn't, replace that fuse just to be sure, then trace back the harness to find the break in the wiring.

White is ground, black is power to trailer battery trickle charge, blue is brakes, green is tail/running lights, red is left turn signal and left brake light, brown is right turn signal and right brake light, yellow is aux power/back up lights. This is the general color coding, there are exceptions, white, black, and blue are pretty much always as listed above, sometimes the others vary. If you find you are having trouble, post any further questions here, I'll be glad to help out. Curt

Pull all of the bulbs and try it using a tester to each light. I have seen a bulb that would contact both posts and kill the lights. Hope this helps. Mike