We have no electric brakes on the trailer when using the brake pedal. Our F350 with Tow Command is hauling a 2 axle trailer with 12 x 2 Dexter electric brakes.

One side of the trailer jacked-up so I can spin the wheels. When I am in PARK, truck running and I set the gain and slide the manual level on the Tow Command the brakes lock-up immediately. If I press on the brake pedal, nothing happens. I can hear the magnet in the electric brakes weakly energizing but not enough grab to stop the wheel spinning.

Is there something wrong the Tow Command or am I not able to test in driveway? Is the truck sensing no movement and therefore no voltage to the brakes? Is the ONLY way to test, to get on the interstate and lock-'em up?

When underway (in DRIVE w/TRAILERING on) I can hit the brake pedal and again, no noticeable effect. Also in DRIVE when I slide the manual control, there is resistance from the trailer, but it seems weak, despite how high I set the gain.

Any ideas?

 

Most trailer brake controllers work off inertia. If the vehicle is not changing speed, very little brake power is applied to the trailer.

When moving, the manual slider on the brake controller should lock up the trailer brakes. It is possible the magnets on the trailer are worn. If you have a multimeter, testing the trailer brakes is easy. Just do a google search for electric trailer brake troubleshooting.

 

This would depend on the gain. With the gain properly set, the manual slider should not lock up the brakes.

I agree, however, that at full gain you should probably be able to lock the brakes and if they don't, they probably need checked and adjusted.

 

Tow Command doesn't work below, I believe, 15 mph.
Yes, that's right...............great engineering.

 

Well, I think is was fixed in some subsequent year, but for 2005 Tow Command doesn't work below 15 mph. I agree with the previous post...... great engineering.....

 

Below 15 mph Ford figures you can jump out in case of a brake failure.
Remember to tuck and roll.

 

Thanks for the great feedback & info. I am still at a loss of how to check/inspect the system. I did a complete rebuild of the trailer brakes and adjusted them accordingly. I am only trying to figure out if everything is working OK.

As I said I can energize the magnets and stop the wheels with the truck in PARK and using the manual slider. When I use the truck brake, current flows to the magnets (I am using an indicator light to check continuity) but the trailers wheels do not stop. Not enough current, the indicating light is lit, but faint.

How do I know if this is normal for Tow Command in PARK? Or if I have a short (in the brake light circuitry for instance) that is causing the reduced current?

How do I test this in a garage setting?

 

Sounds like the master cylinder pressure sensor is bad.. this is what feeds the tow command processor.

under warranty have Ford fix it.

Sam

 

On my 2008 F-250 there is so much electronic "brain" built into the TBC that I can't even understand the explanation of how it works. They didn't seem to work driving around the neighborhood but if I touched the levers it jerked me to a halt. Stop and go driving through Chicago was a breeze, the "brain" always knew just how much pressure to apply. Very smooth stops and starts. (MORRYDE pin box didn't hurt).