brakes lock when backing up - rewire?

O

okla1967

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May 31, 2010
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I (after 5 years) am having a problem with my trailer brakes locking when backing up on flat ground. My Cadillac Escalade EXt has the std round 7 pin flat female trailer wiring, as does my Pul-toy aluminium trailer. There are only 5 wires.

I recently pulled my trailer/boat out of winter storage and when disconnecting in the dark with not lights, I failed to disconnect the trailer wiring from the truck and pull the wires (5) out of the male trailer connection fitting.

I rewired using the std GM wiring diagram and wire color code. All lights work correctly.

Pulled home yesterday and when I tried backing up the brakes lock up. The automatic surge slides to the rear and they lock.

Because there is no "override" wire to connect to the back up lights, and there has never been a problem before, I am puzzled.

Anyone have any ideas?
 
Y

Yellow Yota

Petty Officer 2nd Class
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Jul 23, 2009
Messages
122
Re: brakes lock when backing up - rewire?

Where is your 5th wire going?

If you have a solenoid on your trailer that disables the brakes when in reverse, the 5th wire needs to hook up to the backup light pin on the plug. NOT the brake pin. That one is for electric brakes only. You need the signal from the backup lights on the tow rig.
 
dingbat

dingbat

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Nov 20, 2001
Messages
17,032
Re: brakes lock when backing up - rewire?

The wire to the solenoid goes to the center pin on the 7 pin connector.
 
M

mike343

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May 4, 2009
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Re: brakes lock when backing up - rewire?

Everything was fine until you did this:

I recently pulled my trailer/boat out of winter storage and when disconnecting in the dark with not lights, I failed to disconnect the trailer wiring from the truck and pull the wires (5) out of the male trailer connection fitting.

I rewired using the std GM wiring diagram and wire color code. All lights work correctly.

If the clearance /tail lights work the ground is probably OK. You need to get a voltmeter and test for 12v on the blue wire while in reverse. If it's not there that's the problem. Or you blew a fuse during your modifications.
 
O

okla1967

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May 31, 2010
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Re: brakes lock when backing up - rewire?

thanks, I'll check that out. Preliminary effort to contact Pul-toy Trailers, Inc seems to indicate that they are out of business. Just great! Trying to reach boat builder to see if they know anything. In the meantime, I will try your idea.
 
dockwrecker

dockwrecker

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1,392
Re: brakes lock when backing up - rewire?

And possibly a sympathetic failure of the cut out solenoid? Or as I had to do on mine, run a hard ground to it. I've heard nothing but "not so great" about the cutout only solenoids vs. the backup pressure release type that return fluid to the master. But of course, first confirm it's getting power with the backup lights on. The factory blue wire is a brake controller wire! The backup is color purple. The solenoid however will probably have a blue wire on it. Very confusing sometimes. Regardless, power should be at the center pin in reverse and the solenoid hooked to that. Now the burning question: You aren't by chance using a 7 pin to 5 wire adapter plug nowadays are you? If so, your solenoid is hooked to the brake controller which is why it won't work. Standard 5 pin adapters are for electric brakes, not brake releif solenoids. Ditch the 5 pin on the trailer, go get a blank female 7 pin connector from U-haul for 10$ and wire it trailer side. You'll never have a problem again regardless of what you tow it with.
 
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