Haven't been able to feel the trailer brakes on the last trip out. Yes, I know that if I have them adjusted correctly and right on point that this would be a good thing. However, this is not the case this time.

Been doing a little chasing as to where I may place blame and begin to look for the cause. Here is what I have tried and the results:

I have tried the truck with another trailer, all though it was a 20' utility trailer and not a 40' 5th wheel. If I set the impute to 10 and use the manual slide to apply brakes the tires would lock up. If I pulled the cord on the trailers emergency brake switch..again the brakes locked full and the tires would drag when the trailer was pulled.

I have hooked up to the 5th wheel setting the impute at level 10 with the truck pulling the trailer at idle, when I applied the manual slide lever the trailer would stop the truck and trailer. However, if I applied throttle the trailer would move forward not locking the tires or dragging them.

I hooked up to the 5th wheel and pulled the emergency brake switch cable and the trailer pulled forward with only idle speed. I tried this with both the umbilical cord plugged in and unplugged from the truck. The batter on the trailer is at full charge.

I assume that the issue is trailer related and not truck due to the results when attached to the utility trailer.

Where do I move to next? I assume it would be to make sure that the wires are all attached at the axles where they are exposed.

The part that is throwing me off is that it would slow the truck down at level 10 with the manual brakes slide applied. This gives me cause to believe that there is current going to at least one of the brakes.

As I understand it, the two wires at the brakes are not dedicated as one must be positive and the other a negative. If I were to use a test light with one end to one wire and the other to the other wire would I get a light is there was electrical flowing to the wires?

Give me some of your knowledge and teach me where I am over thinking the problem or over looking the obvious.

Thanks in advance,
Jon

 

If the trailer pulls forward with the break-away pulled at idle, yes the problem is absolutely with the trailer. Pull the break away on mine and it will throw you through the dually's windshield and the dually can move it only by dragging the tires while they are locked.

So I would be guessing the problem is a the first wheel where the brake leads come first. All it would take is a bad connection to get the results you are reporting. Since your brake controller is not reporting a trailer disconnect, you have a least a partial connection to complete the circuit.

Do you have an amp meter and know how to use it?

Steve

 

When was the last time you inspected the brakes on the 5th wheel trailer?

 

easy enough to have someone step on the brakes while you listen at each wheel of the 5th wheel.


Listen for a buzz....no buzz, no brakes.

 

Might also need to adjust those brakes on the trailer too.


Lift up each wheel, spin it and adjust till to can start to feel the drag of the brakes.


Unless...you have self adjusting brakes.

 

The OP started out by saying he was sure the brakes are adjusted correctly, so unless he is wrong about that, pulling the break away has to lock em up unless there is a wiring issue.

Steve

 

Yes and no. I have one, but not sure how to use it. But, I do have a son in law how does. Time to get some use out him it would appear!!!

 

Easy to do. Make sure your seven pin is unplugged from your truck. You can check the amp draw on the break-away leads usually easiest to access in the junction box behind your pin.

I am going to assume you don't have a clamp meter, but has a more common meter that read amps draw in series with the connection. If that is the case, just disconnect one of the break-away leads and put one meter lead on one of the wires you disconnected and the other lead to the other wire so power passes through the meter when the brakes are drawing power.

You need a meter that will read up to 20 amps or you will blow the fuse in the meter if the brakes are working. If your meter only reads 10 amps (some do) in which case if you don't care to blow the fuse, you will know you have more than a 10 amp draw and the magnets are all working.

Now pull the pin and your meter should read about 12 amps, 3 amps per wheel. If you see at least 10 all the magnets are on-board, anything less and one or more magnets are on vacation. If you have a good amp draw, there is something mechanical going on at the wheels.

Make sense?

Steve

 

RV Tech, Thank you. As soon as the storms pass over I will give it a shot.

 

If I were to cut the blue wire coming from the brake away switch and attach the multi meter inline between the two ends of the blue wire would this give me the reading that I am looking for?

And yes, the meter I have is a cheap HF freebie with a 10amp limit. So if I blow the fuse it's not big deal as I have a number of them laying around in the garage.

I did hook the trailer umbilical cord up to the truck yesterday and had the wife step on the brake pedal. I could hear the buzz at each wheel, however one wheel was not as loud as the other 3 wheels were.

Would the brake away switch be hard wired to the RV battery at the post or tapped in line somewhere along the wire harness?

I so greatly appreciate your help and sharing of knowledge with me and others who may be following this thread.

 

Yes, you can cut the lead and connect as you are suggesting, however, you can also just undo wire nuts in the junction box and not cut anything. And you know, you do have to pull the pin in the break-away to complete the circuit to the brakes. It's easier to do this with two people, one to hold the meter and one to pull the pin. When I do this, I use a clamp meter which negates the need to cut a lead, but I realize most folks do not want to invest in that piece of equipment.

Good luck,

Steve

 

The wires in the junction box are all connected with the use of crimp connectors. Wire nuts would have been much easier if used.

I called my SIL who said he does have a clamp meter. He is going to come give me a hand. Could we also use the clamp meter to check the individual amp at each wheel with using the wire at each wheel?

 

You have a son-in-law with a clamp meter? Amazing, most folks don't even know what they are. Yes, you can use it at each wheel, but check first pulling the break-away and just using it there to see if you need to check individual wheels. No need to break any leads using a clamp meter, it just read by putting it around the lead and pulling the pin.

Steve

 

Here is an update. Not sure if his amp gauge was reading correctly.

When we tested the break away switch we got "O" reading. I did once again check and with the break away switch pulled out I can still pull the trailer with my truck at idle.

I also tried pulling the trailer once again with the brake setting at "10" and applied the brakes with the manual slide function. No resistance felt and the trailer rolled freely.

With the brakes applied you can hear a buzzing at each of the 4 brakes. Tested the 4 brakes with the amp gauge and 3 of the brakes gave a reading of .03, 1 brake did not give a reading at all.

I also checked the wire leads that come down from the belly of the trailer leading to the brakes, these gave a reading of .03 to .04.

We also checked the blue brake wire at the junction box, it was .03 to .04.

The blue brake wire down near the lower trailer plug on the truck we did get a reading of .07.

I am going to purchase a new clamp style amp gauge tomorrow and retest for double checking the results. My SIL said that sometimes his gauge has had issues reading with the clamp.

At this point I am questioning if the break away switch is closing completely when the pin is pulled and completing the circuit causing the brakes to lock.

I am also wondering if I may need to replace the cord on the trailer. As well as the aftermarket 5th wheel plug harness that plugs into the factory trailer harness.

Of course I am guessing out loud here.

 

The one brake with no reading is something to follow up with but I would concentrate on the brake away issue first.


That may solve the issue.