Trailer update

The other post had enough pictures get confusing, so Ill
continue from here. I replaced both damaged ends, truck and
trailer. I wired it according to the diagram that came with the
new ends. I have brake lights when I step on the pedal.
Taillights and turn signals work correctly. The blue wires for
the brakes are connected but I have no light on the brake
controller. If I hook the black wire on trailer trailer wire to the
blue wire on the truck, the light on the brake controller comes
on. That is what I did before and the brakes worked but
locked up. What am I doing wrong?

If the constant 12v wire is hooked to the brakes it will lock up. The controller may need attention if that is not it. Jim

Isn't your plug out of time? Maybe not but it looks funny to me.

the brakes worked but locked up. What am I doing wrong?
Get a voltmeter out. Is the black wire +12v?
If it is your brakes work, +12v on black wire bypassed controller.
My electric brakes work on 4 to 5 volts. You apply 12v to brakes for emergency stopping via a break away switch and battery on trailer.

When I worked my brakes I applied 12v form a battery to brake wire and measured 12 amps. That will lock up wheels.

Get your meters out. My brake controller only works when truck is moving and it notices I'm slowing down.

Good luck. The wiring on truck doesn't look factory.

If you disconnect the black wire from the blue, and push the brake pedal, do the brakes lock?

If so, the stoplight voltage is somehow getting to the brake magnets.

Look for a crushed cord, somehow the signals are getting crossed.

That the light on the controller comes on with the black wire connected is good, but the controller is only looking for a source to ground. It doesn't know a brake magnet from a light bulb.

With a test light on the blue wire from the controller, the only time you will get a signal is with your foot on the brake AND pushing the test slide. The light should start out dim and get brighter the further you push the test slider.

Isnt black constant 12v from truck? for remote use like charging?

The slots in the plugs are lined up, colored wires are matched except for extra black and red wire on trailer. I checked the wires from the plug to the junction box on the trailer and all are good.

Dont worry about colors so much. Wires get changed and whatever color wire is available gets used sometimes. Look to see which wire goes to the trailer brakes. Apply the manual brake slider on the controller, use a multimeter to see which wire from the truck gets that voltage. Wire the plugs so they match up.

(quoted from post at 19:26:31 08/09/21) The slots in the plugs are lined up, colored wires are matched except for extra black and red wire on trailer. I checked the wires from the plug to the junction box on the trailer and all are good.

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I would forget the colors for now, identify the function attached to each blade in the vehicle socket, and make a drawing of what is where. The same function should be on the matching blade of the trailer plug. Identify the ground blade on the trailer plug to trailer with an ohmmeter or continuity tester. then you can use a battery (ground to trailer) to put power to each of the other blades on the trailer plug to identify what it is actually powering and compare to see if it is the correct blade to match the vehicle socket.

These two pictures may help as far as identifying which blade handles which function. The 7 way traditional standard and the 7 way RV standard use different colors for some functions but the blade for each function is the same for both (The White, Blue, and Black colors are the same functions on both). Thus another reason to concentrate on function not color.





This post was edited by Jim.ME on 08/09/2021 at 04:55 pm.

What power setting is your brake controller set on? Are the brakes locked all the time or only when you step on the brake

What make of vehicle are you running? Try googling that make's trailer wiring diagram and see which wire is for what. This is one for a Dodge 2500.

A tester that plugs into the truck plug can be very helpful. It enables you to eliminate any problems with the truck before going on to the trailer.

They came on only when the brake is applied or I turned on the turn signal. Someone said that by hooking it it to the black wire instead of the blue one, that it was taking power to the wrong place and making lights and brakes act up. When the blue wire from the controller is hooked to the blue wire on the trailer, I get no light on the controller. Starting to wonder if the problem is farther back on the trailer. I need to have a neighbor hook up to the trailer and see if it works on a different truck. If it works on a different truck, then I know it's my trucks problem, if not, then its a trailer problem. As of right now, all lights work as they should, just no brakes.

(quoted from post at 07:53:25 08/10/21) They came on only when the brake is applied or I turned on the turn signal. Someone said that by hooking it it to the black wire instead of the blue one, that it was taking power to the wrong place and making lights and brakes act up. When the blue wire from the controller is hooked to the blue wire on the trailer, I get no light on the controller. Starting to wonder if the problem is farther back on the trailer. I need to have a neighbor hook up to the trailer and see if it works on a different truck. If it works on a different truck, then I know it's my trucks problem, if not, then its a trailer problem. As of right now, all lights work as they should, just no brakes.

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If there is a problem in your trailer why risk damage to the neighbor's truck components? You can hook it to another truck if you want, but given the industry standard blade positions for each function is the same as shown in the pictures, a test light will quickly tell if there is a problem on your truck side or not. Or as mentioned buy a plug in tester and check the truck.

You said you wired the new plug by the instructions that came with it. Where the instructions by wire color or function? Many new plugs come with the RV trailer wiring colors. As I posted before; the Traditional standard wiring (used on utility and equipment trailers) and the RV trailer standard wiring use some different color wires on the trailer cords, but the same plug terminal location for each function. Blade position and function are the keys, wire colors can vary and can't be trusted unless you have verified the actual color for each function of your wires. Make absolutely sure the ground circuit is good from the truck to the trailer.

(quoted from post at 04:53:25 08/10/21) They came on only when the brake is applied or I turned on the turn signal. Someone said that by hooking it it to the black wire instead of the blue one, that it was taking power to the wrong place and making lights and brakes act up. When the blue wire from the controller is hooked to the blue wire on the trailer, I get no light on the controller. Starting to wonder if the problem is farther back on the trailer. I need to have a neighbor hook up to the trailer and see if it works on a different truck. If it works on a different truck, then I know it's my trucks problem, if not, then its a trailer problem. As of right now, all lights work as they should, just no brakes.

Click to expand...

A tester that plugs into the truck plug can be very helpful. It enables you to eliminate any problems with the truck before going on to the trailer. They are not expensive and very readily available.

see alot about wire color and matching trailer to truck. Not a trusty thing. I had a 2001 chevy truck and hauled my 4x8 and 5x10 trailers everything worked that should when plugged. upgraded to a 2008 gmc and very little worked when plugged in. Stop by the gm shop and they said my new truck wasnt wired the same as the old even though they were blood brothers. I am with the folks label wires by function then you will be easy pleasy. Best of luck!!