Trailer brake wiring question( Mystery Now Solved)

[dclark1946]

Another question after crawling around under our new KZ Spree TT.

The wiring to the rear of the brake drums is only connected on the driver's side. The wires coming out of the back of the drums on the other side are taped off. Is the other side fed through the axle tube or what? The trailer brakes draw about 11A when supplied with 12V when using our electric trailer dolly.

I think I had measured brake current draw on each of the 4 wheels using a clamp on Ammeter on our 2007 Spree.

Mystery solved:

Thanks for your inputs. Based on those I was able to resolve this. My initial impression that the passenger side brake wires were not connected but just taped off was based on what I saw from the drivers side under the trailer where I could clearly see the wiring coming out from the plastic under belly liner and connecting to each of the brake drums. One of the wire pairs was laying across the top of the leaf spring which are mounted on top of the axle. I will need to reroute that pair. When I looked across to the other side to see how the wiring was routed I could see nothing but the wires coming out of the drums with tape on the ends.

This morning I decided to climb under the passenger side for a closer look. I did see a pair of black wires exiting the axle and connecting to the drum wires so what appeared to be taped off wires was really the connection to the wires coming out of the axle tube. Black wires, black brake drums and less then optimum lighting coupled with not knowing that manufacturers had started feeding the brake controller power down the axle tube led to my initial wrong conclusion. I am now a little wiser.

[dclark1946]

myredracer wrote:

dclark1946 wrote:
Another question after crawling around under our new KZ Spree TT.

We have a 2014 version of the same Spree model (except it has the different bathroom layout). I would suggest looking at the wiring in the A-frame area. Ours was poorly done. Plenty of corrosion and water trapped in upside down wire nuts inside the 4x4 metal box. The positive wire from the battery was completely loose in a ring terminal and fell right out when I touched it. You may fix the wiring at the brake drums, but you also need the connections from the trailer's wiring to the umbilical cord to work, especially for braking when you need it the most some day. I completely redid the connections and installed a watertight PVC junction box. I also redid ground lugs to the frame due to corrosion.



The brakes in our TT are not grounded via the axle tube and have 2-wire cable spliced to the 2 brake wires. The wiring is awfully small gauge though and I plan to upgrade it when I eventually take down the underbelly sheeting.

This our 2nd Spree TT and wiring does not appear to be their strong point. Have also found poor AC & DC terminations at the converter/panel (including completely loose wire at a breaker) and a couple of receptacles with reverse polarity.

Thanks for the input. I will inspect the wiring and connections to make sure they are going to be reliable.

[MEXICOWANDERER]

Thank goodness you found this and corrected it. It could have caused a genuine disaster.

[BB_TX]

dclark1946 wrote:
............. I did see a pair of black wires exiting the axle and connecting to the drum wires .........

Mine are the same. I did not like the unprotected wires coming out that metal hole in the axle bouncing down the highway. I pulled the wires out slightly, wrapped several wraps of electrical tape around them, and pushed them back in. I check them every year for wear around that hole.

[myredracer]

dclark1946 wrote:
Another question after crawling around under our new KZ Spree TT.

We have a 2014 version of the same Spree model (except it has the different bathroom layout). I would suggest looking at the wiring in the A-frame area. Ours was poorly done. Plenty of corrosion and water trapped in upside down wire nuts inside the 4x4 metal box. The positive wire from the battery was completely loose in a ring terminal and fell right out when I touched it. You may fix the wiring at the brake drums, but you also need the connections from the trailer's wiring to the umbilical cord to work, especially for braking when you need it the most some day. I completely redid the connections and installed a watertight PVC junction box. I also redid ground lugs to the frame due to corrosion.

The brakes in our TT are not grounded via the axle tube and have 2-wire cable spliced to the 2 brake wires. The wiring is awfully small gauge though and I plan to upgrade it when I eventually take down the underbelly sheeting.

This our 2nd Spree TT and wiring does not appear to be their strong point. Have also found poor AC & DC terminations at the converter/panel (including completely loose wire at a breaker) and a couple of receptacles with reverse polarity.

[Charlie_D_]

Chris Bryant wrote:

dclark1946 wrote:

The wiring to the rear of the brake drums is only connected on the driver's side. The wires coming out of the back of the drums on the other side are taped off.

If the wires coming out of the back are taped off- those brakes did not get hooked up. That would concern me on a new rig (what else did they forget?).

Follow Chris' advice. I am surprised that no one else caught the fact that the brakes are not tied into the wiring. Although run through axles they must exit and tie into the brakes at the back of the drums. There is no other way to wire the magnets.

[Chris_Bryant]

dclark1946 wrote:

The wiring to the rear of the brake drums is only connected on the driver's side. The wires coming out of the back of the drums on the other side are taped off.

If the wires coming out of the back are taped off- those brakes did not get hooked up. That would concern me on a new rig (what else did they forget?).

[dclark1946]

Thanks to all for all the good inputs.

[dclark1946]

RoyB wrote:
You can also use a campers compass held up close to the brake magnets and you should see the needle deflect when the brake signals are applied.

Some brakes also make a tone noise when activated. Both my trailers do this... You have to be real close the wheels to hear it...

each brake magnet will draw around 3AMPS DC current if the full 12VDC is applied. So add your brake magnets and see if your DC current is close to that number for all brakes... Four brake magnets could draw as much as 12AMPS DC CURRENT when 12VDC is applied.

Roy Ken

Roy. I assume the compass test is with the wheel and drum removed to expose the brake magnet? Does 11 A sound about right for 4 brakes. I think that is about what our old trailer pulled.

[RoyB]

You can also use a campers compass held up close to the brake magnets and you should see the needle deflect when the brake signals are applied.

Some brakes also make a tone noise when activated. Both my trailers do this... You have to be real close the wheels to hear it...

each brake magnet will draw around 3AMPS DC current if the full 12VDC is applied. So add your brake magnets and see if your DC current is close to that number for all brakes... Four brake magnets could draw as much as 12AMPS DC CURRENT when 12VDC is applied.

Roy Ken

[Gdetrailer]

downtheroad wrote:
Probably through one of the axles.....

Downtheroad.. That wiring diagram IS messed up.

According to Dexter axle, the grounding of the brake magnets should not be done at the trailer frame.

Instead ALL of the grounds for the magnets MUST return to the CONNECTION at the tongue of the trailer.

This is important for proper brake operation.

For the OP, there will be a pair of wires running INSIDE the axle tubes.

The problem with this setup is the wire is free to move around inside the axle tube. This movement over time will break the wires or chafe the insulation to the point you get intermittent shorts in the wire.

If you are having any problems with the brake wiring, bypass the wires going through the axle tubes.

In some cases it is easier and faster to just run all new heavier wire from the tongue to the brake magnets. Doing so eliminates the subpar OEM wiring.

[BB_TX]

If you want to make sure those brakes are working. Jack a wheel slightly off the ground, pull the emergency break away plug or have someone step on the brake pedal or hit the manual brake switch, rotate the wheel to see if the brake locks up. Dont leave the break away plug out but long enough to check one brake at a time.

[downtheroad]

Probably through one of the axles.....