Advice please...Trailer Brakes Disconnected

[Patty]

Towed 5er camping this past weekend, only about 70 miles from home. In the short trip there I got a chime (alert) from the EVIC saying "Trailer Brakes Disconnected" and I think "Check Trailer Brake Wiring". It would come on and then go away by itself every 10 minutes or so. I pulled over to check and the trailer was securely plugged into the dealer installed box receptacle. I unplugged and re-plugged it in and continued on to the campsite and the chime went off about 5 more times on the way there. A few times I manually hand activated the trailer brakes and they worked every time. This is a 2011 truck (and trailer) and I never felt the trailer brakes were all that great, but no troubles. The trailer weighs about 11,000 pounds and I always have the ITBC set at 10 with never a wheel locked up.



I tested it at the campsite with a 7-spade circuit tester and the brake, back-up, signal, tail and marker lamps all brightly illuminated the tester when on, but the trailer brake light on the tester only dimmly flickered when activated. I assumed it was another faulty dealer installed MOPAR plug as the first one they installed 1 year ago had poor internal connections right off the start and had to be replaced the day after it was installed (all MOPAR harnesses etc). I then checked the factory bumper plug and it did the same thing with the tester (dim, flickering light on tester but it was on).



My question is, is this normal or should the test light for the trailer brakes have fully illuminated like the others did? Should I suspect the trailer wiring (it's only a 1 year old trailer as well). I now assume that the problem is in the truck or truck wiring (plug or harnesses) since both plugs exhibit the same when tested. Thanks in advance for any advice you have to offer. Leaving Friday for a 1500 mile trip and hope not to be delayed with a visit to the dealer (my electrical know-how is limited).



Thanks,

Patty

 

[RonD]

I had the very same problem 4 months ago. The EVIC is seeing a short, it shuts down to save the brake controller. In my case that sounds exactly like yours I found a brake wire clip came loose inside the drum the supports the magnet wires, the wire was rubbing on the side of the brake drum causing the short, I would have all 4 wheels pulled with the brake drums, and you will find the problem,

 

[Hoefler]

Remove the in bed plug from the system. Unplug it from the bumper mounted receptacle and plug the factory harness back into the bumper receptacle. The plug relocation kits have had their issues, especially in wet weather. Plug the trailer into the bumper receptacle and my bet is, your problems will go away.

 

[HBarlow]

RV and utility trailer wiring is famously cheap and sloppy. Often the trailer manufacturer runs the brake wiring down one side of the trailer than uses crimp connections to attach wires to run across to the other side either somewhat loosely attached to the axle tubes or inside the tubes. In either case the wires often become chaffed and bare over time and create shorts. Check trailer wires also.

 

[Patty]

Thanks RonD, Hoefler and Harvey. I can't rule out anything just yet but I still believe the problem is at the truck in this case and not the trailer because of the tester I used (it coincidentally was something I ordered from Geno's and it arrived Friday morning just before we left!). Has anyone used one of thiese testers before? Like I said, the tester to me indicates that all the lights are and will work properly on the trailer. But as far as the electric trailer brakes go, if I plug in the tester to either receptacle on the truck, manually activate the brake controller by sliding the bar over, or push the brake pedal, shouldn't the circuit tester light for trailer brakes fully and brightly illuminate if everything on the truck is functioning properly?

Hoefler, I'll try returning it to factory by removing the harnesses after work and see what I get. Ron, this is a Montana trailer also. Harvey I agree, many things about these trailers are cheap and sloppy, not just the wiring!

 

[RustyJC]

Depending on how much trailer braking the controller is providing, the voltage on the trailer brake wire can be substantially less than 12VDC, thus your dim test light. Trailer brakes function on current (amps), not voltage. The more current fed through the magnets, the more braking force is produced. The current is modulated by modulating the voltage required to produce that current level.



Rusty

 

[HBarlow]

If your tester doesn't light up brightly on the braking out pin just like the other lamp or 12v hot pins do that is a problem.

 

[RustyJC]

The trailer brake controller, if no trailer braking is being called for, uses a milliamp signal pulsed through the trailer braking circuit to detect whether or not the trailer brakes are connected. If it can't establish continuity, the milliamp signal is lost and the Trailer Brake Disconnected warning is triggered.

Using Ohm's law (E = I x R), the voltage across the test light is going to be the product of the milliamp signal sent out by the brake controller times the internal resistance of your test light, not to exceed 12 VDC. When no pulse is being sent out, the voltage will be 0 VDC.

Example: If the brake controller is wanting to establish a 50 milliamp signal through a circuit with 20 ohms resistance, the voltage required to send 50 mA through the circuit is 0. 050 x 20 = 1 volt. That's not going to light an incandescent bulb nearly as brightly as 12 volts.

Rusty

 

[Patty]

Thanks a lot Rusty! With what you have provided and what RonD said earlier, I think the truck controller/wiring/plugs and harnesses are fine and there is an intermittent short (or could this also be a poor ground?) somewhere in the trailer wiring. To prove this to myself I took the same tester to my 2011 Dodge 1/2 ton and got the same results... bright test indicators for the other lights and a pulsating dim test indicator for the brakes, but the light was on.



I now assume with this type of tester all you can do is establish that milliamp signal, and if there is no light on the tester whatsoever, then there's no continuity and you have a problem in the trucks wiring somewhere. So I guess that means the problem lies in the trailer wiring and I have some searching to do. Thanks again.

 

[Patty]

If your tester doesn't light up brightly on the braking out pin just like the other lamp or 12v hot pins do that is a problem.

This is what I thought would happen as well. There was no "manual" supplied with the tester outlining what to expect in this situation but I guess it did the job.

 

[HBarlow]

The tester I have looks like an ordinary seven pin male and has seven tiny led lamps, one for each pin in the receptacle.

To test the trailer brake controller and truck wiring you have someone manually depress the trailer brake override and look for that lamp to light.

If it lights, the truck side should be okay. If it does not, the brake controller or associated fuses and wiring are defective.

 

[HBarlow]

Patty,

What brand of trailer brake controller are you using? That may be the problem and may be contributing to difficulty of diagnosis.

I use a BrakeSmart that taps directly into the brake line. When I slide the manual braking lever to full on position I am applying full 12 volt braking as if I had stomped hard on the brake pedal. No truck movement ie no momentum is required. If I slide the 12 volt tester into my seven pin female connnection I'll see a bright led on indicating full braking.

 

[HBarlow]

Patty,

The BrakeSmart also sends a small test signal out every two seconds (est) and I can see the tester flash the brake output led with a low intensity as it operates but when I slide the manual brake lever to full on I see a bright red led.

 

[Patty]

That's what my tester looks like also, and that is the test I did, having someone activate the controller while I was watching the tester.

 

[Patty]

Patty,

What brand of trailer brake controller are you using?
I'm using the 2011 factory contoller that came in the truck. You may be right in that this set up is tied in differently than an after market controller would be... contributing to the difficulty in diagnosis.

 

[Patty]

Patty,

The BrakeSmart also sends a small test signal out every two seconds (est) and I can see the tester flash the brake output led with a low intensity as it operates but when I slide the manual brake lever to full on I see a bright red led.

I only see the low intensity flash. When I slide the manual lever it doesn't go solid or get any brighter and this is why I originally thought the problem was on the truck end of things. I did also try this same test on my 2011 Dodge 1/2 ton (same controller), and got the same results so I figured this was normal when testing this type of controller with this type of tester. I did however notice that when I plug in the 7 spade tester to either truck, the EVIC doesn't recognize this as trailer brakes (the little trailer picture shows disconnected). This is not a problem as when I plug the trailer into either truck, it does recognize and show connection.

Maybe too much fancy gizmos going on here! I don't believe I would have even known there was a problem if using an after market controller because I dont think they have the same diagnostics that the ITBC has. Like I said everytime I manually activated the brakes while driving they worked. I'll give it a good inspection and clean the connections and hopefully it will be problem solved.

 

[HBarlow]

I have no idea what inputs are provided to the OEM brake controller but suspect it requires inertia to activate so without inertia I have no idea what you should see with a tester. Inertia activation is, IMO, a fundamentally bad design.

The three best brake controllers ever designed and used on light trucks and cars were the old Kelsey-Hayes hydraulic over electric controller and the more modern, computerized, BrakeSmart and MaxBrake. All three tap directly into a brake master cylinder output line and are activated directly by line pressure. Everything else, again IMO, is a pxxx poor substitute.

 

[TFucili]

When the Brakesmart in my(now former)'05 squawked that there was an issue, it turned out to be the brake wire that ran from the left side to the right side of the trailer had been routed inside the axle tube, but had no grommets in the openings, nor any extra jacketing on the wire, so as I came across I-40 in Oklahoma thumpa-thumpa-thumpa, the wire chafed through. It is truly pitiful the poor quality wiring that most trailers come with.

 

[Patty]

I have no idea what inputs are provided to the OEM brake controller but suspect it requires inertia to activate so without inertia I have no idea what you should see with a tester. Inertia activation is, IMO, a fundamentally bad design.



The three best brake controllers ever designed and used on light trucks and cars were the old Kelsey-Hayes hydraulic over electric controller and the more modern, computerized, BrakeSmart and MaxBrake. All three tap directly into a brake master cylinder output line and are activated directly by line pressure. Everything else, again IMO, is a pxxx poor substitute.

Yes I may have to try the MaxBrake in the near future if the OEM controllers braking capabilities continue to disappoint me. My trailer is only 11,000# and I wasn't impressed with the braking when I first set this rig up 1 year ago. Most of our trips are quite local, between 70 and 300 miles one way in rural Alberta. We leave Friday for a 1500 mile round trip which will be a good all around trip to evaluate things like this that could use improvement. Hate to spend money on things I already paid for once but if it doesn't do the job properly... time to go!

 

[d6c]

If I had a dollar for every time the rv 7-way plug and receptacles have failed on me... I could take the lady out for a hell of a nice dinner somewhere... . I am about to go to the big truck plug and end a lot of my frustration and alarms going off on the brakesmart...