First things first... I have a 2001 F250 CC with the 6.8L V10. For a Brake controller, I have a Tekonsha Voyager.

I last towed our travel trailer just over a month ago. No issues. All lights and brakes on the trailer worked great. Fast forward to last night. When I plugged in the trailer, there was no green light on the brake controller. All of the lights on the trailer worked though...

Tonight I backed the truck up to the trailer to try again. Tonight there were no signal lights (which i believe is the same as the brake lights). Still no light on the controller.

I checked all fuses. Both under the dash and in the power control block in the engine compartment. Especially fuses 1, 3, 8, and 28.... None were blown.

Pin numbers are from 7pin wiring diagram here: Trailer Wiring Diagrams | etrailer.com

I sat down and started checking voltages. On the truck, I got ~12V on each of the turn signal pins (5/6) when the flashers were on. I got 2.4V on the brake controller pin (2). I got 0V on pin 3 (Tail & running lights), 4 (Battery Power), and 7 (Reverse Lights). Do these voltages sound right? All of the voltages were measured from Ground, pin 1, to the other pins.

I also checked the trailer plug. I have continuity between every pin and ground, except for the 12V pin. I checked/inspected all of the wires on the trailer and they look ok. I inspected the wires on the truck as well, and didn't see anything wrong.

I'm at a loss of what to check next... Can the fuses still be bad, but not be "blown"? I guess I didn't think to check their continuity when I had them out. Should I try replacing them anyway?

Any ideas/suggestions? Any are appreciated!
Thanks.

 

You keep saying "voltage" throughout your post. If you are using a voltmeter to make checks, you need to stop. Since the circuits you are checking are not under load you will always get a "good" reading even if there is very high resistance in the circuit. You need to either connect the trailer and turn each circuit on while you make your check through various points in that circuit, or use an incandescent test light to make your checks. The test light will introduce a load that will ensure there is at least a reasonable amount of current flow in each circuit.

Be sure to check the connector on the back of the trailer connector on the truck side. It is very common for water to enter here and corrode the wiring.

 

Most commons on trailers is ground connection failure. Dirty connection might work on low amps with lights, but will fail when you hit the brakes with 20 amp.
If you check the ground OK, start with basic on trailer. Do brakes work when you pull break away cable?

 

This sounds like bad grounds, bad connection, corroded pins in plug, etc. Very common as are the symptoms and I totally agree with the above. I use a special tester in these situations, but relying on voltage alone to test gives only a very small piece of the puzzle. You can get a meter reading in almost anything until you load the circuit. Sometimes it takes me hours to find out what connection is bad and dropping current under load.

Bad grounds and corroded plugs probably make up 90% of what I see and account for countless unnecessary purchases of new controllers.

My two cents worth,

Steve

 

Yes, I was checking the voltages with a voltmeter...

Is there some type of tester that can be plugged into the truck plug to at least test that its working correctly? Everything on the truck seems ok... But I know that if its not driving current out to the trailer, it won't work. So. I'm struggling trying to figure out whether its the truck or trailer.

I did take the pig tail of wires off of the truck from where they go into the frame rail to where they go to the plugs on the bumper. All of those wires are ok. And I didn't see any issues where the wires went into the back of the plug.

I will prop up one of the wheels on the trailer tonight and check if the break-away is engaging the brakes.

 

I guess I should also ask if anyone knows or has a diagram of where the grounds are on the truck?

 

Did you actually inspect the wires into the pins so you could see them at the back of the plug. That is a common problem area. If everything is good there and you are worried about the ground pin in the plug, just ground your meter to the frame (scrap a bare spot) and go pin by pin with the other meter probe. Does it make any difference. If everything is good there, so you are seeing 12+ volts (I know it's volts but you have to start somewhere). Plug in your seven pin and go to the junction box on your trailer, the one with metal cover and check for voltage there are each lead with meter to trailer ground. Same readings?

Try that before going further as it is simple to do and takes only a couple of minutes.

Rather than jack up your trailer, hook to your truck with your seven pin disconnected. Pull the break-away and try to pull the trailer. If you have brakes you will immediately know it.

Steve

 

The ground wire from my factory trailer plug on my truck was going to a bolt inserted into frame 1/2 way under the bed. Huge bolt with no corrosion had no connection. I had to remove it, sand the frame, sand the cable end and reconnect.

 

I finally found it...

Right as the wires go into the frame rail, there was a ground wire that by looking at it looked ok, but once I started fiddling with them pulled right apart.

That was a bugger to find AND fix.
Thanks for all the help and guidance!! I appreciate it...

 

It's always the ground (well, almost always)

Steve