Tekonsha P3 brake controller

BruteForce

Well-known member
Hooked up today to get new wheels on the Roadwarrior. Before even leaving my RV pad, I noticed the brake controller flashing red and reading "Overload, NO BRAKES". Sure enough, pulled the manual lever on the P3 and no brakes. Doing some basic troubleshooting and either the P3 is bad or I have a short somewhere in the system. From underneath the 5'er, all wiring looks good. I haven't started taking wheels off to pull brake drums yet.

A few questions:

-Is there a seperate battery for the emergency braking system? I doubt it.. I just assume its using the BATTS in the RV.
-Where does the system ground? I assume somewhere in the generator cabinet where the BATTS and wiring is. But I don't know exactly where.


Tomorrow, I may just buy another P3 to rule that out (or in). If the P3 is good, then its looking like I need to start removing wheels and examining the magnets/wiring on each drum/axle. What a pain!

Any other recommendations appreciated. I have a week-long camping trip coming up next wed, so time isn't my friend right now.
 

danemayer

Well-known member
The trailer brakes are powered by the truck's brake controller. Voltage goes through the truck/trailer connector, and on to the brakes. The only time the RV battery comes into play is if the emergency break-away cord gets pulled (from the trailer breaking away from the truck).

Here's a link to the Dexter Service Manual that may help.
 

cookie

Administrator
Staff member
One pretty common place to look for a short is in the axle. There are wires that run through the axles from one side to the other. There have been reports of those wires having their insulation abraded and causing a short.
If I were in your position I would probably pull and splice new wires in there to eliminate any possibility of bad wires there along with using the Dexter troubleshooting guide that Dan linked to.

Peace
Dave
 

BruteForce

Well-known member
Well, took the truck to the local trailer supply/service shop and they tested the P3 and it passed. So, now its troubleshooting all the wiring from the trailer pigtail all the way to each brake drum! UGH! There has to be an easier way to find a short or bad ground..

As memory serves, the wiring per brake drum comes out from the underbelly and then DOWN into the brake drum. I'll need to climb under again to confirm.
 

WillyBill

Well-known member
@BruteForce,

You may want to start your troubleshooting with the part that's used the most-the plug on the cord where you plug it into the truck. Look for loose Blue wire or another wire strand touching the blue wire or it's terminal.

Good Luck,

WB
 

BruteForce

Well-known member
The trailer brakes are powered by the truck's brake controller. Voltage goes through the truck/trailer connector, and on to the brakes. The only time the RV battery comes into play is if the emergency break-away cord gets pulled (from the trailer breaking away from the truck).

Here's a link to the Dexter Service Manual that may help.

Thanks for the link. How different are Dexter axles from Lippert? I believe my RW395 is nearly 100% Lippert components. Good info in that manual though and thanks for sharing!
 

BruteForce

Well-known member
Pretty sure I just found the culprit. Started the truck up, plugged in the RV pig-tail, then started jacking up each axle/tire to see if they free-spin. Once I confirmed, I yanked the Emergency break/away brake cable and started turning the tires again. All 3 on the door side had the brakes engaged, but while looking across the rig, the center wheel (non-door side) was smoking. I ran over to plug the break away back in and it was smoking too! I had to cut the two wires feeding that thing to keep a fire from starting.

So, now I have to replace likely one magnetic brake assembly AND the break away cable/system. But, it was an easy enough find. I'll report back later today after I replace those two components with confirmation.
 

BruteForce

Well-known member
Updated. Hit the local trailer supply and sourced a full 12" brake kit, installed and then replaced the break away cable since it had melted down during the test.

All is well and I'm ready to tow next Tuesday! Sweet!
 

danemayer

Well-known member
If the brake assembly you removed show any sign of heat damage, you should assume the bearings on that wheel are also damaged and will fail before too long. Suggest you closely inspect them before going out on the road again. Don't ask how I know this.
 

BruteForce

Well-known member
If the brake assembly you removed show any sign of heat damage, you should assume the bearings on that wheel are also damaged and will fail before too long. Suggest you closely inspect them before going out on the road again. Don't ask how I know this.


From what I saw, the magnet fell off and the un-shielded cabling was super frayed. I saw no bearing damage or issues and greased packed everything nicely before wrapping up. Attached to the magnet appeared to only be one super frayed wire..
 

JASMAR

Have Camera Will Travel
Updated. Hit the local trailer supply and sourced a full 12" brake kit, installed and then replaced the break away cable since it had melted down during the test.

All is well and I'm ready to tow next Tuesday! Sweet!

We just had to replace our break away switch. Since it heated up, you may want to replace it also, since it heated up. My 25 cents worth of help.
 
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