Check Trailer Wiring Message on DIC?

kna4977 · 08-21-2008, 08:32 AM

I have an 18 foot car hauler that I use frequently to haul a car to car shows etc. This past weekend I hauled one about 30 miles and when I pulled off the exit, a message came on the DIC to check trailer wiring, then it would flash in and out between that and the trailer connected message. I never hit any big bumps or anything. Just seemed to happen sporadically. When it said check trailer wiring I had no trailer brakes, and when it said trailer connected I did. The lights on the trailer work all the time regardless of these messages. At this point it no longer flashes back and forth between these messages nor does it ever say trailer connected. No brakes either. The trailer wiring looks fine, but I'm not sure whether to look into the integrated brake controller or the trailer itself. My hunch says it is something with the wiring on the truck, maybe a poor ground somewhere, but I'm not sure. Any suggestions would be great. If it's the truck I will just take it to the dealer, but if it's the trailer as simple as it is, I'm not too familiar with electric brake setups and don't really know how to test. Any thoughts???

**ob_1jr** · 08-21-2008, 09:35 AM

So, you have the integrated brake controller...I think it would be something with your truck. Have you looked at the plug on your trailer good? How old is the plug on the trailer? I'm not familiar with the integrated brake controller so hopefully someone that is will chime in.

**Tow Master** · 08-22-2008, 01:52 AM

Im with ob_1jr. Its probably the traielr not the truck. Id crawl under the trailer and check all the wiring and check the plug on the trailer. Have you ever tried using electric grease on the plug?

Hook'em_Horns! · 08-22-2008, 04:48 AM

The controller is indicating a problem with continuity. Pull the head on your plug (trailer) and check for loose connections (they can become loose over time).

Check your wiring all the way back to the hubs, you could have snagged the wiring with road debris and pulled the wire from the clips (I hate these) used at the hubs.

How many miles on the trailer brakes?
How much wear?
Have you pulled the drum for an inspection (easy to do)?

The magnets wear out before the shoes or the brake hardware does. If worn, it's quick, cheap and easy to replace the assembly, just a bolt-on procedure.

timespentsearching · 08-22-2008, 07:36 AM

i work on trailer wireing all the time and 95% of the time it a wire inside of the the 2 plugs (truck or trailer). take the plugs aparts and make sure you dont ahve and pulled put, broken, or over corroded wires. this is where id start

kna4977 · 08-22-2008, 09:20 AM

Quote:

Originally Posted by Hook'em_Horns!

The controller is indicating a problem with continuity. Pull the head on your plug (trailer) and check for loose connections (they can become loose over time).

Check your wiring all the way back to the hubs, you could have snagged the wiring with road debris and pulled the wire from the clips (I hate these) used at the hubs.

How many miles on the trailer brakes?
How much wear?
Have you pulled the drum for an inspection (easy to do)?

The magnets wear out before the shoes or the brake hardware does. If worn, it's quick, cheap and easy to replace the assembly, just a bolt-on procedure.

Alright, I just realized this is more complicated than I thought. Please keep in mind I know nothing about trailer wiring and little if any about electronics, so please forgive my dumb questions.

How do I pull the head of the plug?

Wiring under trailer looked good from a glanceover. Are the wire clips the ones on the backsides of the drums?

Haven't pulled the drums yet for this issue. There's probably 5000 miles on the trailer from new. Trailer has been nothing but trouble from day 1 everything brake related.

Magnets, I didn't know about that and am not familiar with this concept. Replacing the unit? Where do I get one and what am I looking for?

timespentsearching · 08-22-2008, 09:39 AM

here are 2 screws on the trailer plug. take them out and slide the piece of the plug down. it will leave you with the top piece with all the connectors. from there you can go and see the wiring. if you have to use a battery charger and a test light to go through and test all the wires

Johnasara · 08-22-2008, 10:54 AM

I do not know if you checked, But i have a five pin to 7 pin adapter to hook up my trailer. I was having the same problem with brakes and found out it was the adapter. Bought a new one and it has worked since. It too would run the lights but not the brakes.

timespentsearching · 08-22-2008, 10:58 AM

Quote:

Originally Posted by Johnasara

I do not know if you checked, But i have a five pin to 7 pin adapter to hook up my trailer. I was having the same problem with brakes and found out it was the adapter. Bought a new one and it has worked since. It too would run the lights but not the brakes.

yes this is a common problem also. ive had to rewire probably 50+ plugs to make them work. usualy it 6 to 7 that have problems. brake are either on the side then they need to be on in the center or brakes are in the center then they need to be on the side.

Hook'em_Horns! · 08-22-2008, 11:09 AM

kna4977, It’s not really complicated, it may just seem like that. As Timespentsearching said, the most common problem area will be at the plugs, predominately the trailer plug.

Look to see, depending on the type of plug, usually one screw to fasten the cover to the head and 1 or 2 at the base to secure the wires, used as an anchor point to keep from pulling the wires loose from inside the connector. Remove these and slide the cover back to reveal the screw terminals.

Check that each of the stranded wires are all the way in the slots and that the terminal screws are tight. Look closely, as sometimes a strand or two could be left out and touching another terminal. Even when new, these can be loose (and usually are) from the manufacturer. Many times the bundle anchor point is loose, which over time will pull the wires loose from the terminals.

Here are two diagrams for a 6 and 7-way plug to verify the wiring is correct, most likely it is since it has worked correctly in the past. It may be helpful though if some are misplaced while checking them to be secure.

Since you have such a low number of miles on the trailer, you shouldn’t have a wear problem, although there could be a defect in the brake hub hardware, it would be rare.

As to the magnet, a typical electric brake assembly utilizes an electromagnetic activator to apply pressure to the brake shoes.

Here, you see the magnet in the brake assembly where one would see a wheel cylinder with hydraulic brakes on your auto.

The magnet tries to attach to the inside face of the brake drum seen here, which with the wheel spinning will in turn apply the shoes. Add more power output from your controller and it bites harder to apply more brake pressure.

When these wear out, you just replace the whole hub/backing plate assembly as seen here.

Remove the five bolts/nuts in the center, then disconnect your two wires from behind and just slide the old assembly off the spindle. Slide on the new ones, bolt ‘er up, connect the wires and you’re on your way, after adjusting the star wheel from behind, just like hydraulic brakes.

Each backing plate assembly runs $50-$80 depending on the size needed.

Your problem is most likely connection related, but I thought I would throw in this additional info to give you a better idea of how it all works together.