Troubleshooting Reverse Lock Out Solenoid of Surge Brake Trailer Not Functioning

Question:

I have the Demco surge brake actuator installed along with the disc brakes. When I first installed this system I was very impressed with the stopping ability of my trailer. A driver crushed the trailer pigtail to the truck so I replaced it the pigtail. The trailer will no longer back up without locking up the brakes. So I replaced the lock out solenoid. Worked for a couple of days and now it is locking up while backing again. I have tried different trucks as well. Unfortunately no one around the huntsville alabama area will even touch this surge brake system. I dont know why. Can you give me some guidance as to troubleshooting this issue. I am thinking maybe there is not enough current to drive the solenoid so putting a relay to drive it instead of the reverse signal from the truck directly driving it? Thanks,

asked by: Richard

Expert Reply:

The issue is definitely related to the wiring of the reverse lockout solenoid since you have replaced it and still have the same issue. First thing I would check is the pins of your trailer wiring connectors. Most likely there is some corrosion or dirt on the pins of the reverse light circuit which can be cleaned off with some sandpaper to improve the contact which will allow the circuit to have a more solid connection and activate the solenoid.

Another thing I would try is using a probe style of circuit tester like the part # PTW2993 to verify that voltage is making it to the wiring of the solenoid when the vehicle is in reverse.

You can also try improving the ground of the solenoid too as that could be an issue as well. Running a jumper wire to a section of the frame or even back to main ground harness of the trailer.

expert reply by: Jameson C