RobG

Last March on the way back from Utah, my trailer brakes stopped working. My brake controller, a Tekonsha P3(?) -- the one with the fancy color display -- says "No Trailer Connection." I swapped it for an older model and it also doesn't see the trailer. But since I may be traveling again within a couple of months, I figured it was a good time to get them working again.

I was wondering if anybody might have a pinout for a 2006 Keystone 5th wiring box? I have the junction box at the back of the pin opened up, but I'm not really sure what wire does what. I know the blue wire tends to be the brakes, but that's it. I've wired lots of little utility trailers without brakes, but nothing like this big 5th wheel.

Since the brakes are out completely (all three axles), I'm inclined to think that the wiring at the wheels is probably okay... though somebody please correct me if I'm wrong.

Any input is appreciated!

Rob

KATOOM

Are you getting power from the controller? Did you check the trailer fuse(s)?

RobG

The trailer fuses are fine, at least the ones in the fuse panel are. I haven't been able to verify if the controller is sending voltage down the blue wire yet... I need some alligator clips and a long wire, or somebody to press the brake pedal for me.

KATOOM

Start with the basics. Get a test light (if you dont already have one) and then turn on blinkers, flashers, lights, and 12v hot, and test them at 7 pin connector on the truck. If you those work then yes, you'll need some one to touch the brake pedal to see if the brakes pin is also powering. If it is then you'll obviously be moving on to the trailer.

The wires are (should be) all color coded appropriately and you can find the wiring schematics online for all trailer wiring as its typically universal throughout the industry.

If the trucks 7 pin outlet checks out then it simply seems like the trailer brake wire came loose or lost its connection. Once you establish what wire color it is then you'll need that person to touch the truck brakes again and chase that wire. Because yes, you're correct in that if all the brakes arent working then its highly unlikely its not the individual brakes but merely a main connection issue.

1-2-3

Always start with checking grounds first when dealing with trailers.

gorms

The blue wire is your brake output, on the truck side is on the bottom right, ground is bottom left. These two corrode first from my experience, usually inside the connector.

john40

When we were visiting Washington state our 5th wheel brakes didn't work. After checking our trailer I determined that a brake wire was shorting out inside one of the tube axles. I re-routed the wire on the outside, problem solved. When we arrived home I did the other axle and it has worked for years.
John

RobG

I just tested the truck. I made a long jumper wire and went from the brake pin on the connector to my meter. Using the newer fancy Tekonsha, I would see 0.2 V at idle and 16.x milli-volts when I used the brake lever on the controller. I would see no activity at all when using the truck brake pedal (key was on; motor was not running).

Then I swapped to the older Prodigy, the one with the red digital display. I saw 0.5 V at idle and a full 12 volts when using the lever, but again, nothing using the truck brake pedal.

Rob

saggonwaggon91

Use a test light to test the red wire going to the BC under the dash, be sure to get a good ground. Tap the red and hit the brake pedal. That will tell you if there is signal to the BC. Wire colors on the camper generaly run as follows,
https://www.google.com/url?sa=i&rct=...86042917291056

Busboy

Most brake controllers now are inertia type including the P3, they need so "see" the truck slowing down to apply power to the brakes when using the brake pedal. Also when using the lever on the P3 you will only get the max output that the controller is set to, so if set for 7 you will only get max 50% when full lever is applied. Do all the lights on the trailer work ok? If not check the ground wire on the trailer connector where it goes to ground on the trailer. If you pull the disconnect on the trailer do the brakes work? I've seen where the ground pin in the connector can get over heated and melt the plastic so you don't get a proper connection. I have a P3 in my 2011 and recently had a bad brake magnet on my 18 month old low lowboy, the P3 still recognized that there was a trailer back there. If the P3 can't see the trailer you won't get any brake output. I believe it looks for continuity through the brake system where as the older controllers didn't care.

RobG

I tested the red wire today... works fine. I get 12.x volts at the end of the BC's wiring harness.

So.. I guess now that points at the trailer?

All of the lights work on it, btw. I also just installed new taillights because the old ones were cracked and verified all the exterior lights, signals, brake lights, etc worked. Yet the BC still doesn't think the trailer is connected.

By the disconnect do you mean the emergency disconnect? I'll have to check. Is it a safe assumption that I can pull it and have somebody listen to see if the brakes click?

Thanks!'

Busboy

You can't always hear them engage so I jack one wheel just off the ground by the axle then pull the pin to check if that tire will rotate, that's also how I check after adjusting the brakes up.

RobG

(feeling silly)

Yeah I should have thought of that!

Thanks.

Mexstan

A rough check to find out if each brake is working is to hold a compass near the wheel and have someone hit the brakes. If the magnet in the wheel is working properly, the compass should swing to face the magnet. That test will not disclose how efficiently the brake is working, but will give you an idea if there is power going to each magnet.

KATOOM

You can also use a compass if you dont want or cant jack up the trailer axles.....

Engage the trailer brakes and hold your compass around the brake magnet area. If the brakes are working then the compass needle will move due to the electromagnet affecting the polarity of the compass.