Brake Controller Question

[2004fx4]

I have a question for all you guys with a brake controller. First a little back ground. I have had a Tekonsha Sentinal brake controller for about 4 years now. I used to have a regular time brake controller that I hated. In the Sentinal's manual it stated to set the intensity of the brakes by pulling the manual slide and turning up the intensity until the brakes locked up. Then all you do is back it off a bit. I can not do this with this controller. At maximum it still does not lock up the brakes. I just thought it was the trailer, even though I could lock them up with the other one.

Well now it has been bothering me since I saw the new Techonsha P3. I went to a RV store and they told me I should make sure my controller was working right.

Here is my question. When I check at the controller I have a voltage of 13.5 going to it. When the brakes are applied I have a maximum voltage of 11.5 comming out of it. Is this normal? Or should it be the same as voltage in. I also checked the voltage at the trailer plug on the truck, it is 11.5 also. I know that it is only 2 volts. But if my calculations are right that would mean a 15% drop in possible braking.

Could someone please confirm this on their brake contoller?

Thanks

[TCH777]

I would first check to know that it is not the trailer brakes being out of adjustment or worn out.

My P3 is turned up too but I think the brakes are in need of adjustment on my 5th wheel trailer. I towed my trailer with a friends truck who has an older analog brake controller and I had to set the gain on it really high too.

Tim

[2004fx4]

I just had the trailer inspected and everthing is good. The brakes looked new.

[artkelly]

Mine didn't lock up until I had the brakes overhauled. Now I can make them SMOKE.

You should really measure the CURRENT, not voltage, when troubleshooting. Broken wires under the trailer are fairly common and it's easy to run voltage to the break, but hard to get the current to jump the break.

I can no longer find the Dexter manual that specified the current of their magnets, but I think I remember that it was about 7.5 amps per magnet at 12 volts. If you have four wheels, then that's 30 amps for FULL BRAKING.

First, with the trailer battery fully charged, and with the tow vehicle UNPLUGGED--VERY IMPORTANT WITH SOME CONTROLLERS!!!--pull the emergency breakaway lanyard and measure the current. You can either cut open the harness to the breakaway switch and measure it there, or at the battery. It should be close to 30 amps for a tandem axle. Be sure and reinsert the lanyard right away, or your battery will run down.

If it is around 30, then the brake wiring is probably OK. In this case you'll have to reinsert the breakaway lanyard and hook up the tow vehicle plug and measure the current in THE LINE FROM THE TV TO THE TRAILER, NOT AT THE TRAILER BATTERY. You will have to isolate the brake wire and measure the current flowing while you apply full braking with the controller manual slider. This is where a clip-on ammeter is a good thing.

If you get 30 using the breakaway and the same or close (say 25 amps--the controller may not supply as much current as the breakaway switch) using the controller, the actual brake linings are suspect. You may have to turn the magnet zone on the drums. (I did.)

If you get considerably less current, it's between the controller and the harness to the individual brakes. Most likely a connector. Start with the trailer plug, then the controller plug. After that, it's a witch hunt.

If the current from the first lanyard test is low, you have to go under...

You should be able to find the wires for the individual brake magnets somewhere under there. I think the OEM configuration is inside the axle sometimes, but you should be able to find it near the axle.

Repeat the remove-the-breakaway-lanyard test for each magnet.

Everybody (including Tekonsha) used to sell these cheesy clip-on ammeters that you basically hold next to the wire and it gave a fairly good indication of current. They're getting harder to find. Sigh...

AutoZone sells the "Actron / Sunpro Styleline Series 2" Ammeter Gauge Kit" for under $15 that would work. <span style="color: #000099">HERE. </span> It may be a clip-on. Otherwise, you'll have to cut into the wire. In this case, I'd do it at the battery.

Hope this helps. PM if you have questions. Glad to discuss further.

Art

[FairfaxF350]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 2004fx4</div><div class="ubbcode-body">I just had the trailer inspected and everthing is good. The brakes looked new. </div></div>

Unless the brakes have been adjusted, the inspection doesn't guarantee proper adjustment. I did not realize that trailer drum brakes need to manually adjusted. Without the adjustment, I could not lock up the trailer brakes.

As TCH777 said, make sure they are adjusted.

[artkelly]

I found the Dexter manual. The currents PER MAGNET are 2.5 or 3.0 as shown <span style="color: #000099">In This Table. </span>

Hope you didn't go berserk trying to get your magnets to draw 7.5 amps each. [img]/forums/images/%%GRAEMLIN_URL%%/blush.gif[/img]

Art

[NCHornet]

You must be my twin!!! I thought I was reading a post that I had forgotten I had written. I too have the Sentinel and noticed that I can't get my brakes to lock up any more, at full power I slide the slide lever and I can hardly feel a tug on the truck. I just got back from Ohio and I believe the truck was doing most of the braking. I figured after 7 years it may be wore out so I ordered a new P3 controller but haven't towed with it yet. I will hook up Fri or Sat and I will let you know how it goes. The trailer brakes are adjusted properly, I did it myself and there is no reason why they shouldn't lock. I can tell you this P3 controller is a high tech piece of equipment, it allows you to monitor amps, current and many other functions. I will try and remeber to post back. If I haven't by Sunday 9/9 send me a PM.