2nd Gen Non-Engine/Transmission Need assistance with electric brake control trouble shooting.

[tmacc]

We haven't towed anything for a quite a while. We're getting our wood floors finished and even though it's a water base finish, the odor is pretty unpleasant. We're going to rent a travel trailer for the two days that the finishers be applying the finish.

I needed to replace the trailer plug on the back of the truck. When I was checking all of the connections with a multimeter, the trailer brake wire was reading a constant 11.5 volts with out brakes or using the manual slide. The reading didn't change much when I did activate the slide. I've had the Draw-Tite Activater ll for ever, so I figured it was shot and bought a Activator lll. Same results. The blue brake wire reads about 11.5 volts. I checked voltage going into the controler and it's about 12.2 volts. Any idea on what's going on here? Any help would be greatly appreciated.

 

[petersonj]

When I was checking all of the connections with a multimeter, the trailer brake wire was reading a constant 11.5 volts with out brakes or using the manual slide.

You may be seeing a normal voltage reading as a multi-meter does not place a load on the circuit. Try using a test light. If the circuit is good, the test light will not light without using the manual slide. When you use the slide, test light should begin to light (dimly at first) and then get brighter as you move the slide to maximum output.

- John

 

[RustyJC]

Ditto to the above. Brake controllers often apply a "phantom" voltage on the brake output to generate a milliamp current through the trailer brake circuit. That's how they determine that the trailer brakes are connected. If the controller applies the voltage and doesn't see a current draw, it will give you the "Trailer Brakes Disconnected" message. This milliamp current isn't enough to activate the magnets on electric drum trailer brakes, but it can sometimes play havoc with electric over hydraulic disc brakes by triggering the pump to run continuously - that's why the new trucks have settings in the ITBC (integrated trailer brake controller) for electric over hydraulic brakes.

Trailer brakes operate on current, not voltage. More current = more braking.

Rusty

 

[tmacc]

Dang! Thanks guys. Of course, the test light worked. I mentioned the solution to my wife and her response was to laugh and ask how many f-bombs I wasted on this.