I have a 1999 dodge ram 3500 and i have no trailer running lights, ive verified with other vehicals its not my trailer and even used a clamp and spike style test light. Nothing at the pin for running lights when i have my trucka light switch on. I even traces the loom back all the way to under the drivers door right at the ffront wheel well the wire that feeds my trailer plug is a orange striped black wire. I found the wire up by the wheel well and tested again with the test light and still nothing. Was hoping there would be power then id just run a new wire from there back. Anyways after the wire loom makes it to the engine bay it teea off to the fues panel, into the cab, and abs module. I havnt peeled the loom to see where it goes yet . Any idea where to start or what it could be? 

Check pin #87 of the trailer tow relay in the PDC, that is where the wire ends.  Power for it comes from 40A fuse #8 in the PDC to terminal #30 of the trailer tow relay.  Power from the headlight switch goes to terminal #86 and terminal #85 is ground.

So ill take the trailer relay out then stick my test light on that pin while the alligator clamp is clamped to a ground? Is their a diagram somewhere or online that will show which pin is what? And if i dont have power there what should i look at? If i do have power then its probably a broken wire between the PDC and where i checked under the truck by the wheel well? 

This is from a 2002 FSM, but may work for you truck.

 

- John

 

Now how would i go about testing that pin with the relay disconnected? Would i just put my test light across the 2 pins that are the switching terminals #30 & 87?

Testing terminals for trailer tow relay in the PDC.

Tools needed: a Jumper wire and test light.

 

Is there 12V at terminal #30? if no check fuse #8 in the PDC.

Is there 12v at terminal #86 with the headlight switch in the on position?  If no check the headlight switch. 

Is terminal #85 grounded?  With test light prob in terminal #85 and clamp end on positive post of battery is the light illuminated?  If no check        ground G102.

Jumper Terminals #30 and #87 with 16-12 AGW jumper wire. Does the black/orange wire at the 7-pin trailer connector have 12V? If no, then          there is an open circuit (poor contact or broken wire) somewhere between the PDC and 7- pin trailer connector.  

 

 

All testing can be done with ignition switch in off position. 

So ive tested the black and orange wire all the way to under the cab by the driver side wheel well so if there was a break it would be between there and the PDC. The headlight switch should work if the headlights work(which they do) right? Ive checked all the fuses. Where is ground g102 located?

Did you run all the tests outlined above?  That will tell you what to look for and what part of the circuit it is on.

No i havnt been able toco all the tests yet but i feel as though i can rule out a couple things like the fuse that is good, the headlight switch works  and ive traced the wire back to under the wheel well so the break if there is one would be between there and the PDC. Also wheres @Mopar1973Man been/ hows he been doing havnt heard anything from him on here in a while

Imagine and doing good. I'm cancer free but also learning how to live with my new body being I no longer have a bladder or prostate. 

 

Then between @Tractorman and @IBMobile are correct. I would check that fuse in the PDC at #9. Then swap relays just to check that too.

Thats good to hear man hope it stays that way. Deffinetly guna be a new chapter of life, my mum has blood cancer and has had to go through alot as well she always tells me you just gota take one day at a time and enjoy the little things in life, its to short as is even without any problems. Oh and i feel stupid, it was the relay lol, i guess it makes sense that only the running lights would be on a relay circuit while tail lights, power brakes, aux power would have juice all the time. Now my next issue to tackle is the cruise controle it intermittently works, just worked the other day and now it doesnt. Some days when i cycle the key to the on position before starting the truck the cruise light will be on the dash and other days it wont be. Its a vacuum cruise truck btw. Oh and the other day when it did work the light didnt come on the dash and say cruise while it was on