Troubleshooting Dexter Electric Over Hydraulic Brake Actuator Pump that Runs But Brakes Do Not Work

Updated 06/10/2015 | Published 06/08/2015

Question:

Hello, Ive had the system installed on my 38 foot boat trailer for a few yesrs now however this year, there appears to be a good 5 second delay from the time I apply my breaks to the the time I hear the pump engage? if I use the manual switch on the dash, the unit comes on without delay. Im baffled!

asked by: Barry

Expert Reply:

You will want to start by following the troubleshooting tips in the manual for the electric over hydraulic actuator, # K71-651. I have outlined them here for you:

1. Verify that the trailer and tow vehicle are wired according to the electrical schematic shown in “Electrical Requirements”.
2. Re-bleed the trailer brakes. Any air in the trailer brake system causes brake delay
3. if the trailer is equipped with drum brakes, re-adjust the drum brakes to the trailer manufacturer's recommended running clearance.
4. Trailer wiring that is too small can cause slow response
5. Slow response can be caused by brake line restrictions. The trailer brake lines must be at least 3/16” in diameter. Steel tubing is preferred over flexible hoses.
6. Check to see if the white ground wire runs directly to the tow vehicle ground. IT MUST NOT BE GROUNDED TO THE TRAILER ONLY. IT IS IMPORTANT THAT THIS GROUND WIRE RUNS DIRECTLY TO THE TOW VEHICLE'S BATTERY GROUND. NO EXCEPTIONS.
7. Detach all wires from the Dexter Axle E/H unit leaving only the blue, black, white and yellow wires. It is important that the unit is disconnected from any other wires going to the towing vehicle or breakaway switch and breakaway battery. Failure to do so may result in a faulty test.
8. Using a 12 volt battery, connect the white wire to the negative (-) terminal of the battery.
9. Connect the black wire to the positive (+) terminal of the battery. The motor should not run. If the motor runs, the unit may be defective.
10. Leave the white wire connected to the negative (-) terminal of the battery.
11. Connect the blue and black wires together to the positive (+) terminal of the battery.
12. The motor should run and the unit should pressurize
13. If this does not occur, the unit may be defective.
14. Leave the white wire connected to the negative (-) terminal of the battery.
15. Connect only the yellow wire to the positive (+) terminal of the battery.
16. The motor should run and the unit should pressurize.
17. If this does not occur, the unit may be defective.
18. If the unit checks OK, reconnect the wires leading to the trailer plug and repeat steps 9 through 14 at the trailer plug. If you do not get the same results as before, the problem is in the trailer wiring or the electronic brake controller.

Most of the time there is some wiring issue such as a loose connection or weak ground that causes problems.