I want to test out the electrical side of our fivers brakes. I read an article giving the max amp draw for four 10 or 12 inch brakes as 11.3 - 13.3. I can use a 20 amp multi tester. My thinking is to disconnect the house from the house batteries, make sure the breakaway switch still has power, then pull the pin and check amp draw at the battery cable. Is there a hole in that idea? This would be just the first step, letting me avoid taking apart the wires at the hubs. But if the amps are low, I’ll have to get down there and proceed further.

I would use a clamp-on DC ammeter at each wheel looking for about 3 amps.Any excuse to get a new tool ;)

I don’t have a clamp on one. Well, not with me.

I have found that most 4 wheel brakes draw about 1 amp per volt applied.If you can measure the battery voltage at the same time you measure the current you should be near 1 amp per volt.If you are not within 2 amps out of the expected 12 amps at 12 volts then you should check each wheel to find where the problem is.

Snowman9000 wrote:. My thinking is to disconnect the house from the house batteries, make sure the breakaway switch still has power, then pull the pin and check amp draw at the battery cable. Is there a hole in that idea? .Yep. A hole. Do NOT pull the E-brake pin while the 7 pin is attached to the truck. There is a chance doing that could fry the controller. So reconnect the coach battery, and unplug from the TV. The E-brake is designed to be operated off the coach battery, Not the TV power.

Thanks. The truck would not be connected.

Testing electric brakes, Update. | Good Sam Community

valhalla360
Navigator
Nov 07, 2017
What are you trying to test?

Simple first test is to hook up, lift the landing gear by an inch or so and then manually apply the trailer brakes while pulling forward. If they hold they are working.

Now if you have reason to suspect only some of the wheels have failed, then you need to dig into the wiring and amp draw but it will have to be done at each wheel. A clamp on meter is really much easier as you can have someone push the brake pedal while you simply clamp the meter on.
Snowman9000
Explorer
Nov 06, 2017
Thanks. The truck would not be connected.
Terryallan
Explorer II
Nov 06, 2017
Snowman9000 wrote:
. My thinking is to disconnect the house from the house batteries, make sure the breakaway switch still has power, then pull the pin and check amp draw at the battery cable. Is there a hole in that idea?

.

Yep. A hole. Do NOT pull the E-brake pin while the 7 pin is attached to the truck. There is a chance doing that could fry the controller.

So reconnect the coach battery, and unplug from the TV. The E-brake is designed to be operated off the coach battery, Not the TV power.
RCMAN46
Explorer
Nov 06, 2017
I have found that most 4 wheel brakes draw about 1 amp per volt applied.

If you can measure the battery voltage at the same time you measure the current you should be near 1 amp per volt.

If you are not within 2 amps out of the expected 12 amps at 12 volts then you should check each wheel to find where the problem is.
Snowman9000
Explorer
Nov 06, 2017
I don’t have a clamp on one. Well, not with me.
time2roll
Nomad
Nov 06, 2017
I would use a clamp-on DC ammeter at each wheel looking for about 3 amps.
Any excuse to get a new tool ;)

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