I have a 99 Ranger 4.0 and when I hooked my boat trailer up today and checked my trailer lights I couldn't get a left side turn signal on the trailer. The left side turn signal on the p/u worked fine just not to the trailer. I cleaned the plugins on the p/u still no light, so then I disconnected the plugin that connects into the wiring harness and tested that & found that there is no juice to the yellow wire or left side. Does the left side or yellow wire splice into the yellow wire that goes to the left tail light? Is there another way to check to see if there is current going to the trailer harness?

 

Check fuse #3 in your in cab fusebox 7.5 amp

 

Fuse is ok.

 

On 1999 Ranger(last year for separate turn signals in the rear) the left turn bulb on the Ranger uses a Light green/orange stripe wire

A standard 4 or 5 wire trailer connector would use Yellow wire connected/spliced TO the Light green/orange stripe wire
Since Ranger left turn works then my guess is the splice for the yellow wire is bad, it happens, loads of water spray on the underside rear of a pickup

Trailer connectors standard wiring is
Green - Right turn
Yellow - Left turn
White - Ground
Brown - Park
Blue - Brakes

Many drop the Ground and use that for brake lights so they can use a 4 wire connector
Expecting the trailer hitch and ball to be a good ground, it AIN'T, lol
Most trailer light issue are ground issue
But not in your case


1999 Ranger tail light wiring is:
Right turn - Orange/light blue stripe
Left turn - Light green/orange stripe
Ground - Black
Park - Brown
Brake - Light green


If these don't match up then you have 2000 Ranger wiring in a 1999, not unheard of

 

I'll open up the wire loom in the morning and see what I find. One other thing is that before I hooked the trailer up I put a light coat of grease on the ball as it was rusty could that have anything to do with a part ground?

 

It can if there is not a ground wire in the trailer plug, but that would effect all trailer lights, usually intermittent operation, like the ground, lol

But as said, not your issue because other lights were working, and you also tested the truck side of connector and only left turn wasn't working, I just assumed you also tested the other wires on that connector

 

Well I checked the wiring loom this morning and could find nothing wrong. I checked it all the way up to the junction under the drivers seat and finally decided to just let it go for the time being. Then I thought as a last resort I would check all the fuses and on the # 7 slot I found the fuse was bad. I replaced it and everything is working now. It said that it was the right side tail light and trailer light when I was calling it the left side. Oh well at least I found out what was wrong. Thanks for all the suggestion's .

 

Good work

In North America Right side is passenger side, Left side is drivers side, in the UK, Australia, South Africa, Japan and other countries its Opposite, lol

I often avoid left and right and use drivers side and passenger side to avoid confusion