Brake Diagnosis/Repair

[RG_Upton]

Recently purchased a 20' tandem axle utility trailer with one braked axle. At that time, I also purchased an Impulse brake controller and harness connector for the 1999 Chevy 1500 to pull it. After installation of the controller and harness connector, I am getting 12V from the proper two posts of the 7 RV connector at the hitch when the truck brakes are engaged. When connected to the trailer, the controller still gives an error code indicating that it is not connected.

I assume that the trailer wiring is most likely at fault. Is this a correct assumption? If so, can you offer any easy tips for diagnosis? I certainly don't mind yanking off the wheels and drums and poking around, but I have never worked on electric brakes and am not familiar with them.

Thanks,

Russ

 

[firemanpat2910]

first rule of trailer wire hookups ....... check the ground.
2nd rule ........................................ check the ground.

probably 8 out of 10 problems are ground related, do you have a tester or are you using a meter? I have a simple tester from autozone or somewhere that tests my flat 4, and I recall seeing one for a 7 pin. it lights in different colors to tell you whats wrong.

does the trailer have a break away box? if so is battery connected?correctly?
grounded? the pig tail from trailer to junction box, grounded? clean? tight? wired correctly? pinched and shorted to ground?

wires from brakes .. connected? grounded? frayed or pinched?

 

[RG_Upton]

Ground seems good. Lights on the trailer work fine. I have been using a volt-ohm meter.

There is no break-away box. I think I am down to something amiss between the trailer connection and the brake assemblies. I'll have to disassemble and check for what is not quite right.

 

[kevinj]

I am getting 12V from the proper two posts of the 7 RV connector at the hitch when the truck brakes are engaged. When connected to the trailer, the controller still gives an error code indicating that it is not connected.

Just because the truck is wired right does not mean the trailer is. I would pull the plug apart and check for proper connection and ohm the wire from the plug to the brake backer plates.

 

[kentrodngun]

Maybe my story will help - I too had an error code on my controller and my first thought was that it was the ground (usually is!). Code was intermittent as well. Testing proved it wasn't the ground and I finally pulled the drums to see what was up. Surprise, the wires going to a couple of the brake magnets were broken. Not wanting to mess around, I just bought four new magnets and replaced them. All is right in my trailer world again . Good Luck.

 

[Farmwithjunk]

In the previous few post's, most all the common issues have been brushed upon. Check the truck's wiring through the plug. If that's OK, go on to the trailer's BRAKE wiring. Most trailer manufacturers "daisy chain" the brake wiring. One bad wire anywhere along the way kills everything brake related. (with no effect on the lighting circuit) Start at the front and work your way through everything. Be on the lookout for bad grounds. 99.9% of the time, that's where the problem will be. Also, check for a bad PLUG (both male and female) I had the female plug go bad on mine, just months after the original install. It LOOKED fine, just didn't make connection on ONE pin (mine was the lights, but it could well be the brake pin on yours)

I've seen some trailers wired with grounds from the brakes wired to the front of the trailer. I've had much better luck with a ground tied to the trailer frame as close to each wheel as possible, then from the male plug directly to the trailer frame.

Also saw a bad magnet kill an entire brake circuit.

Good luck.

 

[George2615]

When you purchased your controller did you have to run a wire back from the controller to the 7 pin plug pin #2 or was the blue wire already installed? Wiring should be as follows on the 7 pin plug on back of the truck:

pin1 White - ground
pin2 Blue - from the brake controller
pin3 brown - park/tail light
pin4 black - 12V hot from battery
pin5 yellow - left turn
pin6 green - right turn
pin7 orange - (not always used, when it is it's usually for back up lights)

If all wiring is correct then double check the ground connection as others have said. If ground is OK then you may have to trace trailer wiring at the wheels for continuity.

 

[RobertN]

You should get 3 pins with power when the brakes are applied. Pins 2, 5, and 6 should have power. Pins 5 and 6 are your brake light/turn signal. Pin 2 is your brake controller. 5&6 have to have power to light up both brake lights. Pin 2 just gets power to the brakes.

Recheck the truck first. Then check the entire harness on the trailer. I have seen lots of trailers rewired to match an incorrectly wired truck, and vica-versa. There are standards for the 7-wire connector/socket pinouts.

Also, wire color may not match the wire function... Don't go just by wire color.

I have found the following page to be very helpful:
http://www.marksrv.com/wiring.htm

 

[RG_Upton]

Thanks for all the replies. I will verify truck side first (again) and then proceed to the trailer. I'll post back when I get a chance to work on it. This has slipped down the priority pole a ways and I have to clear up some other to-dos first.

Russ