3370 RL Low Voltage at Brakes

[Clarence62]

Hello all. I don't seem to be getting anywhere near the braking power that I should be. I am getting 6.3 volts when the brake is depressed and the brake controller is at 100%. I am getting a strong 12.7 volts at the junction box at the front of the trailer. I am curious about how the wires get routed to the brakes and if there are known problem connections. Does the wire stay as a light blue? I have the large area open where all of the wiring and piping go through and am slowly trying to chase the problem. Thanks for any help.

 

[Dahillbilly]

wiring color can & does change, mine are black at the axle tubes.v You'll just have to track down the wires & see what you find

 

[Roller4tan]

Some go thru the axle tubes from one side to the other. They rub inside and chafe off the insulation and go to ground. Or the connections are corroded. You need to trace the wiring.

 

[centerline]

the voltage will decrease as you get closer to the axles.. this is normal, as the brakes work by applying voltage and current to the brake coils, which are GROUNDED and become MAGNETS.... so depending on how many coils there are and the wire size and length of run from the tow vehicle, will determine how much voltage loss you will have... turning up the "braking force" on the controller only turns up the voltage on the brakes, causing the coils to MAGNETIZE harder, applying higher brake pressure....

the brake wires can rub thru ANYwhere they touch a surface, as the axles take every shake, rattle and vibration of the road that you never even feel, and if the wires arent secure and protected as much as possible, it WILL cause you troubles... another place the wires are prone to grounding out is at the retaining clips holding the coil wires to the brake arm inside the drum.... and you generally need to remove the clip to inspect the wire, as simply looking at it doesnt always show the damage....

also... the trailer brake systems installed on tow vehicles after about 2012 are not conducive to using it as a power source to check the brake system of the trailer.. its just better to use an independent power source (10ga hot wire with fuse/CircutBrkr) to touch to the brake wire of the trailer. (the trailer ground circuit must be connected to the ground of the same power supply......
the readings from this will be more accurate, and with a simple wire tracer, you will be able to find any shorts or breaks in the wires....

the other irritating PROBLEM is, sometimes the wires are worn and ONLY ground out when the wires are shaking/vibrating as its moving down the road... this is harder to find but gently moving the wire as you test it often causes it to show itself....

and disconnecting the coils from the brake wires at the backing plates can isolate the wire from the tow vehicle to the axles, for seeing if its the problem, and then checking the ohms of the coils at the same location can further tell if there is an obvious problem inside the drums... the ohms for the coils should be 3.7 to 4.1... more or less resistance indicates a problem, nor should either wire, individually, from the coil have a "draw" on it, which would indicate its grounded somewhere...

I can make it sound confusing, but its really a simple process once you get set up with the multimeter, wire tracer and an independent power supply....

 

[Clarence62]

Thank you all. I am slowly working through this. Very tedious job. LOL

 

[wdk450]

the voltage will decrease as you get closer to the axles.. this is normal, as the brakes work by applying voltage and current to the brake coils, which are GROUNDED and become MAGNETS.... so depending on how many coils there are and the wire size and length of run from the tow vehicle, will determine how much voltage loss you will have... turning up the "braking force" on the controller only turns up the voltage on the brakes, causing the coils to MAGNETIZE harder, applying higher brake pressure....

the brake wires can rub thru ANYwhere they touch a surface, as the axles take every shake, rattle and vibration of the road that you never even feel, and if the wires arent secure and protected as much as possible, it WILL cause you troubles... another place the wires are prone to grounding out is at the retaining clips holding the coil wires to the brake arm inside the drum.... and you generally need to remove the clip to inspect the wire, as simply looking at it doesnt always show the damage....

also... the trailer brake systems installed on tow vehicles after about 2012 are not conducive to using it as a power source to check the brake system of the trailer.. its just better to use an independent power source (10ga hot wire with fuse/CircutBrkr) to touch to the brake wire of the trailer. (the trailer ground circuit must be connected to the ground of the same power supply......
the readings from this will be more accurate, and with a simple wire tracer, you will be able to find any shorts or breaks in the wires....

the other irritating PROBLEM is, sometimes the wires are worn and ONLY ground out when the wires are shaking/vibrating as its moving down the road... this is harder to find but gently moving the wire as you test it often causes it to show itself....

and disconnecting the coils from the brake wires at the backing plates can isolate the wire from the tow vehicle to the axles, for seeing if its the problem, and then checking the ohms of the coils at the same location can further tell if there is an obvious problem inside the drums... the ohms for the coils should be 3.7 to 4.1... more or less resistance indicates a problem, nor should either wire, individually, from the coil have a "draw" on it, which would indicate its grounded somewhere...

I can make it sound confusing, but its really a simple process once you get set up with the multimeter, wire tracer and an independent power supply....

Sounds like a good argument for electric actuated hydraulic disk brakes. No wiring beyond the hydraulic actuator in the front compartment, just hydraulic tubing lines.

 

[Clarence62]

Sounds like a good argument for electric actuated hydraulic disk brakes. No wiring beyond the hydraulic actuator in the front compartment, just hydraulic tubing lines.

If we decide to keep this one for awhile, I will look at that

 

[Dahillbilly]

If we decide to keep this one for awhile, I will look at that

went with the disc brake system on our 40' toyhauler 5th wheel what a difference in braking

 

[centerline]

Sounds like a good argument for electric actuated hydraulic disk brakes. No wiring beyond the hydraulic actuator in the front compartment, just hydraulic tubing lines.

the problem people are encountering is that with the integrated trailer brake controllers in modern tow vehicles, if it sees a problem in the trailer brake system, it will cut the power temporarily as it notifies the driver that there is a problem.... in the mean time, there are no brakes on the trailer....
after a few seconds it WILL reset, until it sees the problem again, then it cuts out.... so with it working like this, the tow vehicle cant even be used as "test" power while working with a VOM or test light trying to find the problem.....

in the older tow vehicles, they didnt care if you had a short in the trailer brake wiring, and it would continue supplying power to the circuit and actuating the OTHER brakes on the trailer, until the short got so bad that it would blow the fuse.... at least we had brakes until then, whereas, the modern systems WONT EVEN TRY to keep the braking action happening, but just cuts out leaving you without.....

this is a fairly well known complaint that the NHTSA is looking into to see if its a danger..... I wouldnt think it would take very much looking to see the problem...