I've been troubleshooting trailer brakes for a number of days. Thought it was the brake controller so I bought a new controller since I wasn't getting a voltage increase on the (blue) wire going to the receptacle on back of truck. I fired up the brake controller and now have a voltage increase at pin on receptacle (blue) based on how far I push down the manual switch up to 10 volts when all the way depressed. I connected the trailer and checked the voltage on the camper end (blue wire again) with the sleeve pulled back and grounded on the truck and I get .13 volts at no load and .23 volts at load. Shouldn't the voltage vary just like it does when not connected? Do I need to get the trailer out on the road to test the brakes. Is that the only way to do it? When I press brake with trailer connected I don't hear any type of hum or click at the wheel wells of the camper on either side so I'm puzzled. Any advice is much appreciated folks!
1995 Powerstroke pulling a 1995 prowler 24C,
sounds like some how you are reading the trailer battery no load... fix that first.. and somehow the TT and TV batteries with load... the breakaway pin isn't pulled is it??? either way something is wired wrong and you could cook the new controller...
Love my mass produced, entry level, built by Lazy American Workers, Hornet
You may have a short to ground on the brake wire in the trailer. A common chafe point is where the brake wire goes through the axles to feed the other side. That would explain why you are measuring a fraction of a volt. A brake magnet resistance is about 4 ohms so 4 in parallel should measure about 1 ohm if you measure the brake line at the trailer with the tow vehicle disconnected. May measure a touch more than 1 ohm considering the resistance of the wire and the leads on your meter. It shouldn't be too hard to visually inspect the wiring under the trailer.
I've been troubleshooting trailer brakes for a number of days. Thought it was the brake controller so I bought a new controller since I wasn't getting a voltage increase on the (blue) wire going to the receptacle on back of truck. I fired up the brake controller and now have a voltage increase at pin on receptacle (blue) based on how far I push down the manual switch up to 10 volts when all the way depressed.
I connected the trailer and checked the voltage on the camper end (blue wire again) with the sleeve pulled back and grounded on the truck and
I get .13 volts at no load and .23 volts at load.
Shouldn't the voltage vary just like it does when not connected? Do I need to get the trailer out on the road to test the brakes. Is that the only way to do it? When I press brake with trailer connected I don't hear any type of hum or click at the wheel wells of the camper on either side so I'm puzzled. Any advice is much appreciated folks!
My guess is the controller applies a small voltage to the trailer brakes all the time, just to see if the brakes are connected, thus the 0.13 volts.
The 0.23 volts while you have someone apply the brake manually indicates to me that you have a wire that is grounded or a bad magnet. Start by separating all the wires that the trailer brakes go to.
Lets say that you have the main wire go to the left side and right side. Cut that wire or even each of the wires going to each trailer magnet or brake drum. Then you should have 8-10 volts on the braking wire. If you don't have that many volts, can you check the amps? If you have more than 1 amp flowing, it is surely going to a grounded wire.
Then reconnect one brake wire at a time, until you see a very high voltage drop, or amperage increase. If amps increases to say 15 amps on one magnet, but only 4 or 5 amps on all the others, you have found the problem. Hook up all the good magnets, and tow it someplace to get fixed. Being able to use 3 of the 4 brakes, it should be fairly safe to tow. If more than 3 brakes are bad, consider a tow truck is not that expensive compared to moving the trailer without brakes and getting into a accident. I wonder how well that will go "Officer, I sort of knew the brakes where bad, but thought my truck should stop sometime after applying the brakes" . . .
I guess the very first thing to check (I would think you already did this) is look over all the brake wiring, and see if one of the wires has worn insulation, and is touching ground sometimes.
Sears sells a nice clamp on amp meter that can measure DC amperage by clamping it around a DC wire. It is a lot more expensive than a AC only clamp on meter, so make sure you get the right one. Only about $90 nowdays, I spent over $300 for a amprobe version about 15 years ago.
With that meter, you can measure AC and DC amps accurately. You can also take power from your trailer battery and with one wire connect to the trailer brakes for a short time, giving them full 12 volts. You must be measuring the amperage while doing this and have a 15 amp circuit breaker inline with this wire. I am sure that you will trip a 15 amp fuse instantly, and will be able to get the 15 amp circuit breaker to hold for a few seconds at a time once you get rid of the short circuit.
You don't want to apply a full 12 volts to the braking magnets more than about 3-5 seconds at a time, except in a panic stop situation. But you can apply 12 volts while testing, just monitor your amperage, and stop if it exceeds 15 amps. 12 amps X 12 volts = 144 watts, kinda like a toaster heating element warming up that magnet, it will get really hot quickly if left on very long.
You can actually have someone with a compass next to your wheels when you turn on voltage to the magnet, if it is not working right, the compass will not point north at the wheel. This is a quick test that some RV repair places use to determine what wheel to take apart first when looking for a magnet problem. Of course the trailer needs to be pointed north or south for this to work right. If the compass is pointing north at the wheel, it will not move even if the magnet is working or not.
If you separate each wire, then amperage is 0 amps (no wires connected to any trailer brake magnet) you can hook up one trailer magnet at a time, and check it's amperage, if less than about 8, it should be OK. If one is much higher, or 0 amps, that is a problem magnet, that rim and drum must be taken apart to find the exact cause.
On the 2009 and UP F150 ford truck the built-in brake controller requires the vehicle to be going at least 10MPH before the brake controller will work with just pushing the brake pedal. You may be running into somthing like this... When I first got my 2010 F150 I went thru the same deal only to find out it was suppose to be that way. I don't like not have the brake pedal hold my trailer when stopped at a stop sign on an incline. I have to reach down and hold the manual lever over to do this now with my newer truck.
Don't know about the Dodge trucks but being a 1995 model I doubt it is doing this.
Check with etrailer.com as they have some good sample trailer wiring schematics available on line.
My Posts are IMHO based on my experiences - PM me Roy and Carolyn
RETIRED DOAF/DON/DOD/CONTR RADIO TECH (42yrs)
K9PHT (Since 1957) 146.52M
2010 F150, 5.4,3:73 Gears,SCab
2008 Starcraft 14RT EU2000i GEN
2005 Flagstaff 8528RESS
I think that my controller should override the if I push the manual button and the even the manual button is not applying voltage all the way to the brakes although when disconnected from trailer the manual brake does send voltage back to connector pin on the truck. I feel pretty sure it must be a grounding issue on the trailer end of things. I'm going to check the resistance on the blue signal on the connector with the trailer disconnected to see if it will show the 1 ohms at a miminum. If I see less than that it should tell me that I have a bad ground on the trailer or a broken wire so I'll start tracing the wires and grounds for issues! Thanks for the help all!
I had the same problem with our '85 Wilderness and '65 Chevy Van. First I rewired all of the connections right at the brakes. I got rid of all the Scotchlock connectors which were all corroded and replaced the 20 guage wire with 14 guage going thru the axle to the other side. I replaced the connector cable between the trailer and tow vehicle. But the brakes still didn't work too well. Turns out the connections at the TV brake switch were bad, so after replacing those, brakes work good now.