Prodigy P3 Overload Warning

We had this problem in the summer of 2001 but before we were home it was good so on our 1st trip south for the winter it started again. over load and the short signal came on with the trailer brakes working or not working or really working. Wire going though the rear axle had a bare area and was shorting off and on depending on toad conditions plus on that axle a magnet was bad.

Easy fix for the rv shop in Stockon ca.

chevman

You have a P3 use the diagnostics available. Set the P3 to indicate the current draw.

Most 4 wheel trailers will draw about 1 amp for each volt applied.

Monitor the current when you are stopping.

Got a compass....a real hand held one

Hold it down next to wheel where brake magnet is

Then have someone apply trailer brakes via manual level on brake controller

Watch for deflection of compass needle
No deflection....magnet not energizing

Thanks to all for the good tips. The part that has me stumped is how to figure out which magnet/wheel is causing the problem. I did mess with the P3 diagnostic, but that measures amps on the whole system.

I give the compass test a try first, but suspect all are working until the brake assembly on one of the wheels is torqued to engage the brake shoes against the drum. Then something gets shorted...a bare wire or a bad magnet. Then it quits when the brake is released.

The only solution may be to cut the wires on one magnet at a time until the warning doesn't pop up going down the road. Would rather find an easy way to figure it out in the driveway though.

Might be seeing a disk brake conversion in my future - sure tired of the drum brake problems.

Larry gave you good advice. The way most manufacturers run the wires is down one side and then through the axle to get to the other side. The inside of the axle is not smooth and over time vibration wears holes in the insulation. As the wires move the bare spot touches and shorts. This is a very common cause of intermittent issues.

Larry's advice is good - I should reroute those wires outside the axle as an improvement. The predictability of my overload warning makes me think that is probably not my problem though. If it were a bare wire in the axle it seems an overload would occur at various times when braking, not just when the rig comes to a complete stop.

My question involves how best to check one brake at a time without removing the drums to visually inspect magnets and wires.

I guess you could lift one side off the ground and pull the emergency cable. this would stop the wheels from turning or check the wires with a meter. Ours had a 2 " bare wire that looked like it was heated close to a weld.. We have as you said a wire on the outside tie wrapped to the axle. Still running the same alpenlite with out any brake issues and same bearings and brake shoes. truck does most of the braking.

chevman

Check the plug. Make sure nothing got in there that could short out. Pretty rare but it does happen. The wires near the brakes are a common failure point. Easy to rub through and short out. Another option is the wiring looks ok is to just rewire it. Usually the wiring in trailers isn't the best. One more thing I thought of is to listen to each one. Like get underneath and get your ear right in there while someone is pressing on the control lever. You can usually hear them.

The easiest way would be to test each axle end brake wires with a clamp-ammeter. Amperage will spike if there is a loose wire or shorting magnet. I've never heard of a magnet failing.

I'd strongly suggest to just rewire the whole brake system. Construct the wiring into a "Star" configuration rather than the typical daisy chain. If an owner wires each brake pair of wires to a terminal strip on the tongue of the trailer, diagnosis is a snap since the pairs are right in front and easily checked with a meter for any faults. The Star configuration will also allow the most power possible to each brake.

Haven't tried yet, but hoping I can reproduce the overload with the trailer sitting. After stopping and sitting still I can pump the brakes all day long and no warning. Gonna take some work that's all there is to it. I'll share what I find....or hopefully find. Thanks for all the good tips.