Electrical ??? (brake switch; brake unit; wiring) HELP!!

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WV05Canyon

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I have a 2005 GMC Canyon that U-haul installed a 7 way plug on it to tow my tandem axle trailer that had to be hard wired in. The brake unit is randomly applying power to the brakes (Brake Unit: Prodigy). Does anyone have any suggestions to fix the issue??? So far I have traced the wires under the truck and there is no damaged to the wire shield, I checked the brake switch blue and orange wire and it seems to be functioning properly with the test light, I tightened up the wires in the 7 way plug on the trailer, and traced the wires on the trailer and found no bad places in the shield. I'm at a lost, so any suggestions would be greatly appreciated!
 
WV05Canyon said:
I have a 2005 GMC Canyon that U-haul installed a 7 way plug on it to tow my tandem axle trailer that had to be hard wired in. The brake unit is randomly applying power to the brakes (Brake Unit: Prodigy). Does anyone have any suggestions to fix the issue??? So far I have traced the wires under the truck and there is no damaged to the wire shield, I checked the brake switch blue and orange wire and it seems to be functioning properly with the test light, I tightened up the wires in the 7 way plug on the trailer, and traced the wires on the trailer and found no bad places in the shield. I'm at a lost, so any suggestions would be greatly appreciated!
Click to expand...

What about the Prodigy unit itself?  Does it have a gain control? Do you have a meter to mesure the
output of the unit with the 7 way disconnected? Is there a self-test mode on the Prodigy? )Should say
in the manual)...also is the unit mounted at a "funny" angle..is is a gravity/momentum control type?
Does the unit apply brakes when you are stopped and still?

Just some random Q's...

Rich
 
The Prodigy does indeed have a test mode and that should be used to rule out some types of problems.  And it is not sensitive to position or angle, so the mounting of it is not the problem.

It is triggered by the brake light circuit in the truck, so one possibility is that the truck is randomly turning on the brake lights, which could be the brake light switch, something backfeeding into the brake light circuit, or even a problem in the way the Prodigy was wired into that circuit. Did the Canyon have a factory designated wire for brake controllers or did U-Haul add their own?
 
I too feel that the problem is the truck brake light.... Or the driver.

Some folks were taught to drive an automatic with their left foot on the brake pedal..

The "Theory" such as it is is that with the foot already on the pedal your response time will be reduced in a panic situtation (Personally.. Being a coffee-holic I fail to subscribe to that theory)

In practice it causes the brake lights to flicker and/or early brake failure.

Use left foot for CLUTCH.. if you got one.
 
  Does "randomly" mean the trailer brakes apply without the foot brake pedal?  Or do you mean when applying your brakes the trailer randomly works or doesn't work?
  A good check to determine if its in the trucks brake circuit is this: without trailer attached drive to a desired speed and activate the cruise control. Any braking action, commanded or otherwise will de-activate the cruise.
  Next with cruise still engaged slowly depress the brake pedal and see how far it travels before the cruise deactivates. It might be the brake switch is set too far down and you are actually braking the truck long before the brake switch signals the controller to apply voltage to the trailer.
  Last, if the controller has a gain adjustment it might be set too late or the voltage pot may be too low.
 
 
GM had a recall on 2005 Canyon & Colorado trucks to REPLACE THE BRAKE LAMP SWITCH ASSEMBLY...has yours been replaced?
www.automotive.com/2005/49/gmc/canyon/recalls/66202.html
 
my first question would be, does it randomly apply the brakes while driving down the road, or when you push the brake pedal down, it hit and misses?

Don't overlook that it could be the brake controller,just because it is a prodigy doesn't mean they don't have problems too.
 
RV Roamer said:
  And it is not sensitive to position or angle, so the mounting of it is not the problem.
Click to expand...

If I recall correctly, the prodigy does need to be oriented with at least a slight pitch up to the rear.  If the aft face get tilted down on mine, it doesn't show a "C" for connected.
 
If the aft face get tilted down on mine, it doesn't show a "C" for connected.
Click to expand...

The Prodigy can be mounted anywhere from 0 to +70 degrees "nose up" attitude. You may have a bad wire connection and tilting the units pulls  or pushes the wiring a bit to make or break contact.
 
RV Roamer said:
The Prodigy can be mounted anywhere from 0 to +70 degrees "nose up" attitude. You may have a bad wire connection and tilting the units pulls  or pushes the wiring a bit to make or break contact.
Click to expand...

0 to + 70 is correct.  In my case, I had accidently bumped the aft face below 0 degrees and then the "C" changed to ------. I noticed it on the interstate while driving and rotated it upward and as soon as it when above 0, the "C" came back.  The connectors were both secure on the prodigy and the truck connector end.  When I rotated it down again, the "C" changed again to ---- so I think the orientation is important.
 
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