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marpel

notapplicable

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Posted: 05/28/22 06:24pm Link  |  Quote  |  Print  |  Notify Moderator

As per another thread, I have yet to change out the 7 pin cable.

Prior to doing so, I decided to confirm whether the old cable is still usable.

I hooked up the 7 pin to the truck (which recognized the trailer), and ran through the lights/turn signal/brake lights process (can't recall what that process is called) and all lights worked and message indicated no issues.

However, the manual brake controller does not activate the trailer brakes, nor does applying the truck brake pedal.

So, a couple questions:

- Don't really understand the a/m check process. Does it only show the wiring to the various lights is working? In other words, this does not test the full brake circuit?
- if that is correct, no brakes then suggests there is an issue somewhere after the 7 pin cable?
- And if there is an issue at one of the brakes (ie loose wire), will that affect all brakes?

Thanks in advance,

Marv

jkwilson

Indiana

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Posted: 05/28/22 06:52pm Link  |  Quote  |  Print  |  Notify Moderator

How do you know the controller isn’t activating the brakes? Did you use a compass or listen for the hum at the wheels?


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dougrainer

Carrolton, Texas

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Posted: 05/28/22 07:06pm Link  |  Quote  |  Print  |  Notify Moderator

sitting still, the Brake pedal will NOT activate the brakes. But, the manual lever will. Start the truck, use the manual brake lever/button and attempt to pull forward. After less than a foot the brakes on trailer should lock up and stop you. Trailer brakes operate on dc voltage. 12 volts to the brakes is FULL lock up brakes. 1 volt thru 11 volts will activate in increments. Doug

marpel

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Posted: 05/28/22 08:49pm Link  |  Quote  |  Print  |  Notify Moderator

Thanks for the replies.

And I should have been more clear. I actually hooked up the trailer to the truck and pulled it down a few streets, fully applying the brake controller, then applying the foot brake. Both a few times. Absolutely no resistance at all, either method.

Marv

Grit dog

Black Diamond, WA

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Posted: 05/28/22 11:27pm Link  |  Quote  |  Print  |  Notify Moderator

To see if the trailer side is good, jump 12v to trailer side pin for the brakes. Should lock them up tight.
Your truck sounds fairly new. Is there a readout for trailer brake gain?


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jkwilson

Indiana

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Posted: 05/29/22 06:35am Link  |  Quote  |  Print  |  Notify Moderator

marpel wrote:

Thanks for the replies.

And I should have been more clear. I actually hooked up the trailer to the truck and pulled it down a few streets, fully applying the brake controller, then applying the foot brake. Both a few times. Absolutely no resistance at all, either method.

Marv


You have two things to check: Electrical power reaching the magnets and shoes adjusted properly.

To check power, you can hold a compass near the drum just under the center of the wheel and look for deflection when the brakes are applied.

Adjusting the brakes is a little more work and requires jacking up the trailer. This is recommended every 3,000 miles, so it’s possible for the brakes to fairly quickly reach the point they don’t do any braking without regular maintenance.

If neither of those steps help, it’s not unlikely the brakes are contaminated from overgreasing at the factory or later via using a grease zerk on the axle. Determining if this is the issue requires hub disassembly, but if you have any doubts about the brake or bearing condition it’s a good idea to open it up and look.

prichardson

Lafayette, La

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Posted: 05/29/22 07:09am Link  |  Quote  |  Print  |  Notify Moderator

You need to confirm that you are getting brake voltage at the truck side of the 7 pin connector. If not the problem is in the truck not the trailer.

opnspaces

San Diego Ca

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Posted: 05/29/22 08:02am Link  |  Quote  |  Print  |  Notify Moderator

Before you replace any wires see if the brakes are working.

Make sure the trailer battery(s) are showing at least 12.3 volts or more.

Make sure the batteries are connected and any battery disconnect is not in the picture.

Unplug the trailer from the truck, this is very important. Otherwise backfeed can fry the trucks brake controller

Pull the emergency breakaway cable and pin out of the controller

Try to pull the trailer forward a few feet.

If the trailer rolls you have a brake problem.

Put the pin back in the breakaway

Also this just occurred as I finished typing this. Check the entire umbilical for damage. Last year I helped my neighbor replace the plug on his trailer cable as he was already late to leave and had no taillights. The lights still didn't work. Then I looked at the umbilical and it had been pinched in a turn and partially cut through on the bottom.


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Lwiddis

Cambria, California area

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Posted: 05/29/22 08:07am Link  |  Quote  |  Print  |  Notify Moderator

If concerned replace the cable too.


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Gdetrailer

PA

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Posted: 05/29/22 02:51pm Link  |  Quote  |  Print  |  Notify Moderator

Grit dog wrote:

To see if the trailer side is good, jump 12v to trailer side pin for the brakes. Should lock them up tight.
Your truck sounds fairly new. Is there a readout for trailer brake gain?


Don't have to "jump" anything, just pull the emergency breakaway pin then pull forward.. Break away system overrides the vehicles system (vehicle brake controller, wire and socket).

All wheels must lock and hold when break away system is activated.

Break away switch supplies full 12V from the trailers' on board battery.

If break away system does not lock any wheels then you must troubleshoot and diagnose the TRAILER electrical system and the mechanical part of the brakes behind the drums.

If break away locks all the wheels then consider changing the 7 pin connector and cable.

You have a 99% chance the trouble is not the vehicles fault but folks love to blame the vehicle for everything.. [emoticon]

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