I was pulling my trailer last weekend and it feels like I have no trailer brakes. If I slide the manual brake lever on the controller it doesn't seem to do anything but the brake light does work on the trailer. Anyways, I was checking the 7 pin plug and the trailer brake connection has juice when I apply the brakes but it was intermittant, kind of like I was checking the turn signals. I was definitely checking the brakes because the cover for the plug has a diagram of what's what. Is this normal or should that pin have constant voltage?
This all in addition to the left side brake/signal light not working either and that problem is somewhere in the truck..

 

The trailer brakes receive a variable amount of voltage depending on what the brake controller sends. The brakes on the trailer will work more (stop better assuming they are working correctly) when they receive more voltage. More voltage makes the magnets in the brakes grab harder thus applying more pressure on the brake shoes.

To make a long story short, you will see a range of voltage at the 7-pin connector depending on what the brake controller in the cab is sending.

However in your case I would also make sure you have a good ground since you are having other problems with your trailer wiring.

 

What kind of brake controller do you have? When you activate the manual lever do you see any change in the lights on the controller?

My Prodigy gives a voltage readout when the brakes are applied and the highest I've ever seen is around 7 volts and it usually goes up to around 5 during day to day driving. I just went out to the driveway because I was curious what it would read using the manual controller while sitting still.....it went up to 12 volts and stayed there until I released the lever.

You might also try adjusting the brakes on the trailer. Assuming you have drum brakes, it's the same as adjusting drum brakes on a car/truck. You pull the rubber plug on the lower inside surface of the brake and then turn the star wheel inside with a screwdrive or similar tool until the wheel just starts to drag.

 

2-12volts as you turn the controller up

 

Alright, don't give me too much hassle but I have a "cheaper" controller that I got from Summit Racing but it has worked flawlessly since I got it almost 3 years ago.

When I slide the manual lever over, the light changes from green to red, red being more voltage. This controller does not have an LED readout. The light also changes as I adjust for more or less braking power and also as I step on the pedal.

The other problems are definitely in the truck and not the trailer.

I should see a constant voltage though, right? What I did to check it yesterday was to wedge a 4x4 into the seat to hold the brake pedal down. I didn't get my test light out for about 10 or 15 minutes. Would the brake system start to pulse like that after a period of time, if the truck wasn't running, as some kind of a safety issue.

I guess I'll hook up and get my wife to hit the brakes and I'll listen to see if they are engaging. If so, then I'll adjust them but the trailer does not have many miles on it at all. Those brakes should still look like new...

I'll let you guys know once I get back out there to check some of these things out. Thanks for the replies....

 

My dealer seems to think that the problem I have had (same as yours) is in the fuse/relay block. They are replacing it under warranty. I'm still not convinced that is it. Are you sure that the adjustments on your brake controller didn't move? Also how about the brake pads on the trailer?

Just thinking?

Hondo

 

My controller is a Voyager and I use a 1156 bulb in a test lite hooked to the RV connector brake pin with enough lead for me to hang it over the tailgate where I can see if in the rear view. Adjusting the gain on the controller will make the test light brighter or dim. It doesn't require hooking up the trailer for me to check my controller connections. The controller lite changes colors just like it does when the trailer is connected. A smaller (dimmer) bulb in the test lite will reach max brightness too early to be much good, but an 1156 or 2156 works well when you have to work alone.
Nat

 

Dodgezilla,

Since one of the other lights doesn't work, I wonder if you have a smashed or worn through wiring harness somewhere, and perhaps the pulsing is a thermal overload kicking in and out because there is a short to ground?

Might be worthwhile to unhook the controller and trailer, and take a volt reading at the trailer brake plug between positive and trailer brake positions and/or check for continuity between neg/ground and the trailer brake wire.... Then repeat the check at the underdash plug...

Assuming you don't discover the brake wire is grounded or shorted to positive, I would think the next step would be to try to see if the funky pulsing is from the controller or the truck...

What if you unhooked the controller, and jumped a wire on the truck's under dash plug between Positive and Trailer Brakes (with the trailer unhooked).

Then if you still got a pulsing volt reading from the plug at the back of the truck, you would know it was something in the truck's wiring and not something funky in the controller... or vice-verca...

 

you should have straight voltage i think the one to check is on the upper left check on truck alone if you have pulsing there not good problem is on truck after hook up and take apart trailer hook up see if you got any corrosion there same thing appened to me an corrosion got between 2 connectors and grounded them together i cleaned it and was fine after that HOPE I HELPED A BIT

 

Thanks for the replies. I'll be checking it out again this weekend. I don't need the trailer again until the weekend after next. Hopefully I get it figured out....

 

Well I ended up tapping in to the taillight to make the left side trailer lights work and that was pretty easy. As far as the trailer brakes, I pulled the plug off the truck and inspected it then I pulled the trailer plug apart and found nothing. I put them back together and figured I would have to spend some more time on this problem but I did mess with the controller some. I hooked up and drove up the street to turn the trailer around and now the brakes are working fine. Who knows what the problem was???? I guess I'll wait for it to act up again..
Thanks for the responses fellas....

 

Probably dirty connectors then? Get some electrical parts cleaner and dielectric grease.