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Troubleshooting Guide
Unit will not run or brakes are slow to respond. To determine if the unit
is functioning properly, perform the checks outlined below
1. Verify that the trailer and tow vehicle are wired according to the
electrical schematic shown in "Electrical Requirements".
2. Cycle power to reset the unit. If the trailer is equipped with an
on-board battery, disconnect the black power wire to the DX
Series E/H Actuator for 15 seconds and reconnect to the power
source. Re-test unit. If the unit does not have an on-board
battery, please disconnect the unit from the tow vehicle and
then reconnect after 15 seconds.
3. Re-bleed the trailer brakes. Any air in the trailer brake system
causes brake delay.
4. If the trailer is equipped with drum brakes, re-adjust the drum
brakes to the trailer manufacturer's recommended running
clearance.
5. Trailer wiring that is too small can cause slow response (see
section on Electrical Installation Requirements).
6. Slow response can be caused by brake line restrictions. The
trailer brake lines must be at least 3/16" in diameter. Steel
tubing must be used as much as possible. Using too much
flexible hose may cause slow brake response.
7. 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.
8. Detach all wires from the Dexter DX Series brake actuator
leaving the blue, black, white, and yellow wires loose. 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.
9. Using a 12 volt battery, connect the white wire to the negative
(-) terminal of the battery.
10. Connect the black wire to the positive (+) terminal of the
battery and the DX Series brake actuator will click once. The
motor should not run. If the motor runs, the DX Series brake
actuator may be defective.
11. Leave the white wire connected to the negative (-) terminal of
the battery.
12. Connect the blue and black wires together to the positive (+)
terminal of the battery.
13. The motor should run and the unit should pressurize. 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. If this
does not occur, the unit may be defective.
DX SERIES SERVICE MANUAL
ELECTRIC/HYDRAULIC ACTUATORS
17. If the unit checks OK, reconnect the wires leading to the trailer
plug and repeat steps 8 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.
Using the breakaway system to troubleshoot a unit that is not
operating correctly
1. With a fully charged breakaway battery and trailer plug
disconnected, pull the breakaway switch on the trailer.
a. If the unit runs and builds pressure, the breakaway system is
functioning properly.
b. If the unit runs and builds pressure when the breakaway
switch is pulled but will not function under normal operating
conditions, the problem most likely is a defective electric
brake controller or defective wiring between the tow vehicle
and Dexter DX Series brake actuator.
c. If the unit runs but will not build pressure when the
breakaway switch is pulled, the Dexter DX Series brake
actuator may be malfunctioning.
d. If the unit does not run, measure the DC voltage between the
white wire and the yellow wire. If the voltage is less than 12
volts, either the breakaway switch or the breakaway wiring is
defective.
2. After completing the above steps, reset the breakaway switch
and reconnect the trailer plug.
Trailer brakes too aggressive
1. Reduce the gain setting on the electric brake controller.
2. Check brake adjustment.
Trailer brakes not aggressive enough
1. Increase the gain setting on the electric brake controller.
2. Check brake adjustment.
Aftermarket Kits
Description
DX Series brake actuator Fill Cap & Gasket
DX Series Brake Actuator Gaskets
DX Series Compatibility Adapter
Kit Number
K71-685-00
K71-688-00
K58-036-00
2021.02 | 7
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