trailer connector problem

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dtoots1
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trailer connector problem

Post by dtoots1 » Sun Apr 05, 2020 6:42 pm

have a 2015 gmc all terrain sierra....dam internet diagrams do not match up to what i read off the truck...have the lights running, brake lites,turn signals..and flashers am having problem locating the primary brake wire for the trailer brakes...2 axle trailer w/brakes on both and each has two wires both same color....assume one is ground and other primary, but do not find where hand actuator activates power at he back of truck..might be listed in my owners manual haven't looked there yet.

Jim B
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Re: trailer connector problem

Post by Jim B » Sun Apr 05, 2020 7:41 pm

I found the wires for a brake controller were not all in the harness of a 2002 Silverado when I put a controller in it. I don't know about your 2015. Does it have a trailing package? Many of those could add brake controllers using plug in adapters to the factory harness. I am guessing you are adding the controller. Does yours have an open (could be capped) socket to plug the wires to the vehicle connector socket into behind the bumper? Are you using 7 blade RV connectors?

As far as the brake wires on the trailer brakes, either can be positive or negative. They are insulated coil magnets so it doesn't matter which is which.

gaspumpsam
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Re: trailer connector problem

Post by gaspumpsam » Sun Apr 05, 2020 9:31 pm

Usually blue wire is brakes( from truck)

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shinnery
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Re: trailer connector problem

Post by shinnery » Sun Apr 05, 2020 11:25 pm

This is the best info I have on trailer wiring.
https://www.etrailer.com/faq-wiring.aspx
No trees were hurt in the creation of this message.
But, many electrons were terribly bothered.

440IC/602, 2-440ICD/831 MM UBU-LP, 445N-LP, 445E-LP, BIG MO 400-M, 4 Star-LP M5-D, M5-LP, M602-LP, M670-LP, G900-LP, G900-D, G1000 Vista-LP Case 580CK

dtoots1
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Re: trailer connector problem

Post by dtoots1 » Mon Apr 06, 2020 7:22 am

JimB,
and others...problem i am having...truck came with trailering package....however i am hooking up my gooseneck and had to rewire entire trailer...their wiring was poor and connector did not work ...
now, when looking at truck end,,,3 o'clock is actually the left turn signal and 9 o'clock is the right turn signal, center pin is supposedly backup lights, which trailer don't have. ground is white and is at 5 o'clock

Jim B
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Re: trailer connector problem

Post by Jim B » Mon Apr 06, 2020 8:13 am

Are you using the 7 way blade type connectors? That is the one I expect to see on that type trailer. I would print off the picture of the 7 way TRADITIONAL Vehicle and Trailer connectors, from the link shinnery posted, to use as a guide. The positions of the functions are the same for the RV wiring but the colors used are different. You can't always go by the colors but the function locations should match those pictures. Those pictures are good in that they show you the locations for the blade side of each as you look at them, as well as where they are if you are looking at the screw side. I wire to the position shown for a function, even if the wire color is different (colors should be standard but they are not always, so you can't depend on that). If you reference a wire position in a post please say if you are looking at the blade side or screw side as well as vehicle or trailer connector. Looking at the vehicle blade side 5 o'clock is right for the ground. Left turn should be at 9 and right turn at 3 o'clock by the pictures.

I seem to end up wiring/troubleshooting a number of trailers and vehicles for various reasons and, out side of the 7 way round pin plugs on the semis, we are using the 7 way blade type, even on 4 wire trailers as we redo them. I got tired of looking at the pictures all the time so I got a vehicle socket and trailer plug and made test connectors by putting short leads in them and tagging each lead with the function it is for. Put the plug in to the vehicle and it is easy to check with a test light or voltmeter to see if the function is in the right location and if it is working. I can plug the trailer connector into the test socket, hook the ground wire (has an in line fuse in the wire) to a battery negative and use a jumper to feed the function I want to check from the positive post. No running a vehicle battery down that way. Even made up a lead with a flasher so I can operate tail and signals at the same time to trouble shoot grounds.

If you are not finding power for the brakes, or auxiliary power on your vehicle plug, I found some leave a fuse out or have not connected a wire(s) in the fuse panel under the hood. Something to check if that is the case. If your vehicle came with the 7 way plug and a trailer package they should all be live, but you never know until checked out. Is your brake controller integral to the vehicle or is it a separate unit? On you brakes I would recommend running a ground wire as well as power wire for the magnets - not grounding to the trailer frame as some show. I source the ground wire for the brakes from the same location I attach the ground wire from the vehicle to the trailer frame. Hope I'm not confusing you and I'll answer any questions I can.
Jim

dtoots1
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Re: trailer connector problem

Post by dtoots1 » Mon Apr 06, 2020 4:06 pm

JimB,
here we go....
i source directly from the truck female at the rear,,,and facing it from rear o'clock is 3 o'clock is the left turn signal 9 o'clock is right turn signal, i can only assume idjits wiring truck that way, so i wire trlr connector that way no problem..they work..
am not positive just which one is ground, there is aux power and it seems to be 7 o'clock...not hooked up yet nor is the center pin hooked up as not sure what it connects.
without plug in...i have power at 7 o'clock..strictly ground test light to the pull behind hitch. none from any others..and key not on.

so like a clock we have 1 , 3, 5 7, 9 and 11 o'clock pins.(blades)....right now i have ground wire at 1 o'clock position left turn at 3 o'clock and right turn at 9 o'clock....i had running (brown wire) lights at 11 o'clock position but had ground wire was wrong either at 7 or 5 o'clock but running lights did work.

i tested with meter from aux power and run black lead to trlr hitch and have positive connection if i switch leads it shows negative power so aux is power and not ground...but that also shows up as being the case when i touch 1'clock, why i thought it might be ground at 1 o'clock..am i wrong???

also am testing with hand control to try to find power source for the brakes themselves or does that actually run from the brake lights themselves?

looks like running lights might be 5 o'clock position as only other power source with park lights on other than the aux power

Jim B
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Re: trailer connector problem

Post by Jim B » Mon Apr 06, 2020 7:39 pm

I am understanding you are behind the truck, looking into the socket, not the backside where the wires connect to it.

Tail and running lights on the 11 o'clock blade is good. They don't separate them like semis do on 7 round pin plugs.

Left and right turn signals (with brake lights like the truck lights) is reversed from what they should be. If you don't have to hook to other trailers you can wire the trailer to match. (I can't do that as we use several different trucks to haul the trailers.)

Ground should be on the 7 o'clock blade. The ground blade is often larger. That terminal should show no voltage if checked to the truck frame.

Aux power should be on the 1 o'clock blade.

The output from the brake controller should be on the 5 o'clock blade.

I would suggest using the socket ground (7 o'clock) as the ground for testing the truck, not the frame or trailer.

Also some brake controllers put out a small current on the brake wire (5 o'clock) to sense if trailer brakes are hooked up, so you may see power all the time the truck is on at 5 o'clock. I did one recently where I had to hook a brake magnet up (one wire to 5 o'clock and the other to ground to get the controller to act right. If you can, unplug the controller and see if 5 o'clock goes dead for you. that should tell if it is the brake wire. What brand and model is your brake controller? Your 2015 should be wired so that a controller, with the right harness, would be plug and play. Yes, it likely does tie to the stoplight circuit to sense when you are stepping on the brakes.

dtoots1
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Re: trailer connector problem

Post by dtoots1 » Mon Apr 06, 2020 8:48 pm

JimB,
trouble is 2 things...brake controller is actually built into the dash, at least the levers are visible anyway...i do have a camper trailer which seems to have been wired correctly, at least i know the hand operated lever engages the new brakes i had to put on the camper..not so sure on turn signals yet will get someone to view tail side to check.

yes am at tail looking into the socket.

believe that i did originally have ground at 7 o'clock when i had running lights..will try that again

and get aux to 1 o'clock

should then be able to get brake controller checked for power.

gonna try to sort this crap out tomorrow with 7 o'clock as ground!!!! and then go 1 by 1, tho will leave turn signals as is unless that could be creating internal problems?????? and try 11 o'clock for running lights

7 o'clock is what i used for getting lights sorted out...just used hitch to try to find aux...tho that 7 o'clock has power when key off and ground to hitch????

dam pia

Jim B
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Re: trailer connector problem

Post by Jim B » Mon Apr 06, 2020 9:04 pm

Sending you a PM

JWB Contracting
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Re: trailer connector problem

Post by JWB Contracting » Mon Apr 06, 2020 9:10 pm

Try checking the fuse for the brake controller, should be under the hood on a GM, is on my 2010. I use a plug in socket tester from princess auto (Canada) which looks like a 7 blade RV connector that plugs into the truck end and has indicator lights to show what is working or not. Your truck you get a message of trailer connected when hooked up properly or an error message to tell you it’s not.
Jason Benesch

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B Town
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Re: trailer connector problem

Post by B Town » Tue Apr 07, 2020 4:59 am

I have heard the technician may need to turn the brake control module on with a computer, also. Gotta love new computer technology. I had a friend who had to have this programming done. $$$

dtoots1
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Re: trailer connector problem

Post by dtoots1 » Tue Apr 07, 2020 7:54 am

jwb,
yes truck tells me sevice trailer connector and since not all wires connected will continue to do so tip i get er right.

and will check fuses

dtoots1
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Re: trailer connector problem

Post by dtoots1 » Tue Apr 07, 2020 8:18 am

ok here is what i have hooked up.
1 o'clock is aux power.
3 o'clock is left turn signal.
5 o'clock currently is empty..i think is trailer brakes.
7 o'clock is ground.
9 o'clock is right turn signal.
11 o'clock is running lights.

center pin is not hooked up...trk center pin is hole for the male trailer connector...not a blade

have not plugged in until we can agree.

checked both 30amp controller fuses appear ok...little square fuses do not have test pins, usually show burnt when out.

i am also hooking up direct grounds from the wiring harness ground directly to the axle brake wires and to the trailer frame in 4 different locations...
trailer is double axle 16 foot bed ..aluminum trailer...defunct manufacturer from Florida...all welds inspected visually and appear to be solid...no cracks
visible....no floor yet so all is visible....is heavier gauge better for the ground wire?

3500 lb axles.

Jim B
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Re: trailer connector problem

Post by Jim B » Tue Apr 07, 2020 10:21 am

If that is looking into the truck socket from behind the truck, I would try plugging it in and try the lights. if what you have hooked up works right the brakes should also when connected. And yes the center on the blade type connectors are pins.

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