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Left turn signal activating trailer brakes


lockmup68
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Had this discussion embedded in my 2nd Trip Report, so thought I would pull it out and start a new thread for searching ease.

 

Background: my HDT (international 9200i) conversion by 2L in TX. Towing the Teton, the left turn signal intermittently activates the trailer brakes. I ordered a Techonsha brake tester and got around to testing everything yesterday. Right turn signal, only the light activates. With left turn signal on, the LT and brake is activated (although brake signal is not as bright as with the brakes being activated).

 

Left blinker and brake activating video:

http://s1315.photobucket.com/user/lockmup68/media/IMG_1432_zpsrgqwucal.mp4.html?filters[user]=138958194&filters[recent]=1&sort=1&o=0

 

 

Right blinker and brake not activating video:

http://s1315.photobucket.com/user/lockmup68/media/IMG_1433_zpskl0ovyth.mp4.html?filters[user]=138958194&filters[recent]=1&sort=1&o=1

 

 

So started tracing the harness and found this box in line:

http://s1315.photobucket.com/user/lockmup68/media/IMG_1488_zps0qqgrrmw.jpg.html?filters[user]=138958194&filters[recent]=1&sort=1&o=2

 

 

http://s1315.photobucket.com/user/lockmup68/media/IMG_1487_zpsxjilqxqh.jpg.html?filters[user]=138958194&filters[recent]=1&sort=1&o=4

 

 

Anybody seen this setup before?

 

Thanks,

Shannon

Edited by Lockmup68
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Prior rig was a International 4400 and a fiver with electric over hydraulic brakes.

 

Had an intermittent problem with trailer brakes activating primarily when it was raining. Techonsha controller would display random numbers and trailer brakes would grab/release/grab/release.

 

Ended up being a bad ground connection. The bed builder had extended the accessory ground line from the battery using an unprotected butt connector and tucked it up into the frame rail. It ended up shutting me down in busy SE Portland when I was running bobtail.

 

As stated above, check ALL connections.

 

Lenp

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yes, Truck is all LED taillights, but front turns and markers are Halogen, cab markers are LEDs. Trailer, all marker lights are LEDs, S/T/T are halogens (factory setup).

Red Herring alert. Mixing lights will not cause the issues you're having. The on;y cause is electrons running astray. The junction box you posted is full of corrosion, but it's hard to see if there's enough to allow current leakage between 2 of the studs. A more likely cause, given the "quality" coming out of the builder's shop when the truck was built, is wires run poorly and rubbing, or connectors shorting through the insulation. Think butt-connectors squeezed too hard, or with the wrong tool.

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That is a pretty common trailer wiring box, you can pick one up on ebay for 12 bucks:

http://www.ebay.com/itm/161195779657?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

 

I have one on my truck, usually work pretty well. Makes it nice and easy to troubleshoot/repair things later on. Looks like the seal was not so good on that one. I use a little silicone around the rubber grommets on mine to keep the water out. There is some corrosion in your box, but not real awful. For the price of a new box, a handful of good ring terminals and an hour of your time I would replace that box and all the terminals first. That may be your problem, and if not, it will eventually give you one. And it will always end up being a rainy/snowy/slushy day when you are under the truck trying to figure out why the taillights don't work. Change it now on a nice sunny/warm/dry day. I would also examine the trailer plug, open up the back and check for corrosion there as well. Also cheap and easy to change on a nice day. Sounds like you are getting crossover somewhere in the system and those are prime places to look.

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What brake controller are you using? Hone Eagle has a similar issue . But his brakes pulse on the 5er whe he uses his turn signals.

His controler is tapped into the back brake/tiurn signal lights. I have to move said wire to just the brake light. The controller need a .05v to activate/wake up the controller. The brakes, the turn signals are kinda integrated into the brake lights on the Volvo. I need to isolate just the brake .05v from the brake/turn signal combo. This will happen at the rally most likely since it is cold here at the moment.

May not be the same thing as you but may help in your diagnosis

Kevin

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What brake controller are you using? Hone Eagle has a similar issue . But his brakes pulse on the 5er whe he uses his turn signals.

His controler is tapped into the back brake/tiurn signal lights. I have to move said wire to just the brake light. The controller need a .05v to activate/wake up the controller. The brakes, the turn signals are kinda integrated into the brake lights on the Volvo. I need to isolate just the brake .05v from the brake/turn signal combo. This will happen at the rally most likely since it is cold here at the moment.

May not be the same thing as you but may help in your diagnosis

Kevin

 

It's a Tekonsha. I'll get the model tomorrow.

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LED lights will amplify any corrosion leakage between terminals because they don't load down the circuit the way incandescent bulbs do.

 

LED bulbs don't start conducting until there's a couple of volts across them, if the controller needs less than that to activate any amount of leakage will trigger it.

 

Your turn signals and tail lights are loaded by the halogen lights in front, but the brake line only goes to the rear lights so it only has LED bulbs connected to it.

 

If the brake controller is properly connected to the brake line circuit, the easiest and most reliable fix would be to put a load resistor on the brake line. You can connect it to the same point as the controller sense wire. The load resistor will drain away any leakage current coming into the brake line, keeping the controller sense line at ground potential when the brake lights are off.

 

Either something like this:

 

http://www.gearbest.com/other-car-gadgets/pp_575944.html?currency=USD&lkid=10133739&gclid=CMjRov7xotECFUlyfgodlBkGuA

 

Or add a regular incandescent bulb to the brake line and hide it somewhere.

Edited by Lou Schneider
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LED lights will amplify any corrosion leakage between terminals because they don't load down the circuit the way incandescent bulbs do.

 

LED bulbs don't start conducting until there's a couple of volts across them, if the controller needs less than that to activate any amount of leakage will trigger it.

 

Your turn signals and tail lights are loaded by the halogen lights in front, but the brake line only goes to the rear lights so it only has LED bulbs connected to it.

 

If the brake controller is properly connected to the brake line circuit, the easiest and most reliable fix would be to put a load resistor on the brake line. You can connect it to the same point as the controller sense wire. The load resistor will drain away any leakage current coming into the brake line, keeping the controller sense line at ground potential when the brake lights are off.

 

Either something like this:

 

http://www.gearbest.com/other-car-gadgets/pp_575944.html?currency=USD&lkid=10133739&gclid=CMjRov7xotECFUlyfgodlBkGuA

 

Or add a regular incandescent bulb to the brake line and hide it somewhere.

 

FYI, the trailer brake lights are all incandescent..

 

I"m pretty sure I have some resistors I bought for my old F350 that I never put on in the tool box. i might try that first to see if that is really the problem.

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You don't need a resistor if your lights are not LED. Reading over your original post...I've had this cross talk between lights happen many times on farm equipment and trailers. Its almost always a bad ground connection at that light bulb. The circuit completes thru both bulb filaments instead of thru one filament to the ground. SO the circuit is going from the blinker, thru the blinker filament, (finds no ground) thru the brake filament, to the non-powered brake light wire which is providing a partial ground. I would strongly recommend using a good voltmeter to measure your ground terminal AT THE BULB when the lights are on...most likely find it is not grounded.

 

The old 1197?? 2 element bulbs would often get a poor connection between the bulb itself and the sleeve it snaps into. Can't tell you how many of these I've worked on on farm tractors, cattle trailers, etc. Disconnect power. Scrap with knife, use emery cloth, make sure contact points are clean and springs work right at base, sgueeze sleeve slightly with pliers, fill with SIlicon grease and install new bulb.

 

OR the ground wire is corroded off either inside the light or at the frame.

 

If this is NOT the problem, then you have a corrosion issue between the two wires somewhere. Either in the junction box as stated, in the wiring harness, or in the fixture.

 

Adding a resistor may"mask" the problem by lowering the voltage on the wire, but it won't solve it.

 

Actually, the test process I would do is:

  1. Unplug the connector at the truck. Use a DVM to measure the Left turn and brake light terminals at the truck outlet. (Always measure to clean frame ground) If the Brake light wire has > 1-2V with only the Left Turn on, but NOT the Right turn, the problem is in the truck wiring/controller. (Some controllers may have "stray voltage"..if both turn signals cause identical brake light wire voltage, ignore and proceed.). If it does not, proceed to step 2.
  2. Reconnect Trailer plug. Disconnect wires at the Left Turn & Brake light fixture(s) and measure the wires as above. Again, If the Brake light wire has > 1-2V with only the Left Turn on, the problem is in the trailer wiring. Possibly at the junction box...possibly the wires are bare and touching somewhere...(good luck finding it!)
  3. Check the ground wire to the Left Turn light fixture. Measure continuity to the ground (I assume frame).
  4. If the wiring looks good up to that point, its in the fixture/bulb itself. Either ground issue, or internal corrosion problem.
Edited by Jeff- C IL
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Ah, I thought you said above that the S/T/T on the trailer were not LED, but Halogen? Doesn't matter what is on the truck for this problem.

 

I went back and reread your initial post, YOu say that the Left Turn activates the trailer brakes. Do you mean electric brakes, or brake lights on the trailer. ( Sorry, for some reason the photos/videos above don't load for me, so I can't see what you are talking about.) All the posts about resistors made me think "brake lights".

 

If it is the Electric Brakes which are activating...that is different. The brakes are a very low resistance circuit..adding a resistor isn't going to solve anything (the brakes are already to much resistor!) This is...BAD. not only do you definitely have the two wires shorted together somewhere, you are overloading the left turn circuit, (which is why it isn't as "bright") (The brakes could be feeding back thru the controller to turn on the brake lights as well.)

 

If its brake lights, & if the trailer lights are Halogen, the above post still applies. LED...maybe not. Still general principles of checking voltage at different spots apply.

Without actually seeing the complete lashup on your rig, I can't tell anything in any more detail.

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Since both truck and trailer are new to you, break the issue into 2 parts.

Is there any way you can hook the truck to another trailer and check the turn signals, brakes, etc.

Is there any way to connect the trailer to another truck and do the same?

If it's the truck side, sometimes it is easier/faster to remove the old wiring and start fresh. There is a conversion box called Jacklopee found here http://ethitch.com/product/szmyt-et-jackalopee/ That is the best way to rewire and start fresh. It converts the truck signal wiring to an RV signal wiring.

I would guess that there is a short in your system. Which side is hard to tell without individually testing each side. On the truck side, itss usually at a junction box or the older conversion style boxes. On the trailer, there is usually a box located in the pin box or front compartment where the 7-way cable is divided and run to its home destination. It is possible for a stray strand of wire to short itself to another.

I had a short similar to yours, but it was with the running lights dimly blinking with a right turn signal. The issue was in the junction box in the pinbox area. All my wiring was originally done with wire nuts and tape.... there was a strand of wire about 3 inches long that would randomly bounce and connect with another wire or ground itself out.

Using Jeff's idea above and testing each leg of the 7-way plug on the truck side should show you if you have a short.

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