SERVICE MANUAL
DX SERIES ELECTRIC/HYDRAULIC ACTUATOR

www.dexteraxle.com

Introduction ................................................................2
Installation Instructions................................................2
Electrical Wire Colors and Function................................3
Electrical Installation Requirements..............................4

The Dexter DX Series brake actuator is compatible with many electric
brake controllers, but the best performance will be achieved using an
inertial type controller such as the Dexter Predator DX2®. The electronic
timer type of controller is not recommended because these units use a
fixed control that does not sense varying brake requirements.

CAUTION

Electrical Schematic............................................................4

Test Electrical Operation...............................................5
Bleeding and Brake Adjustment.....................................5
Sleep Mode..................................................................6
Electric Controller Unit Testing/Adjusting......................6
Troubleshooting Guide..................................................7
Aftermarket Kits..................................................................7

Limited Warranty..........................................................8
Locations.....................................................................9

!

CAUTION

This is the safety alert symbol. It is used to alert you to potential
injury hazards. Obey all safety messages that follow this symbol to
avoid possible injury or death.

It is the responsibility of the end user to ensure that their electric
brake controller is compatible with the Dexter DX Series brake
actuator. Dexter attempts to provide compatibility with most
controllers available, but is unable to anticipate design changes
that might be introduced by the various controller manufacturers.

Installation Instructions
The following materials are required to properly install the Dexter DX
Series brake actuator. If your trailer is not already equipped with brake
lines, you will need enough 3/16” diameter automotive brake line to
connect the trailer brakes to the unit. Where possible, steel tubing is
preferred.
ƒ Four 1/4" threaded fasteners to mount the unit to the trailer.
ƒ One quart of DOT 3, DOT 4, or DOT 5 brake fluid (from a new
sealed container).
ƒ One emergency breakaway kit - must include a 12 volt, 9 amp
hour (minimum) battery.
ƒ Wire (see Electrical Schematic, page 4.)

Scan to view DX Series
Actuator Installation Video

Introduction

Location of the Dexter DX Series brake actuator is at the discretion
of the trailer manufacturer or owner. When selecting the location, the
following items should be considered:
1.

The shorter the wiring between the unit and the electrical power
source, the smaller the voltage drop.

CAUTION

2.

The unit should be located so that the electrical wiring and
brake lines can be neatly routed directly to the towing vehicle
and trailer brakes. Special care should be taken to minimize
the number of bends and fittings in the brake line circuits.

This manual has been provided to guide you through the process of
installing, operating, and maintaining your Dexter DX Series electrically
controlled hydraulic brake actuation device (also referred to as DX Series
brake actuator). This electrically powered unit has been designed and
manufactured to give safe, reliable power to your hydraulic trailer brakes.

3.

An emergency breakaway kit must be located on the trailer so
that the trailer breakaway cable can be easily attached to the
towing vehicle.

4.

The Dexter DX Series brake actuator is powered from the
electrical system on the tow vehicle. In order for the unit to
function properly, it must have adequate electrical power (see
Electrical Schematic, page 4.)

5.

The Dexter DX Series brake actuator should not be placed in an
area where it is susceptible to damage from trailer loads, road
debris, or from being stepped on. Failure to protect the actuator
from damage can cause the unit to malfunction and void the
Dexter warranty.

Dexter DX Series systems should only be installed by a qualified
technician.

CAUTION
Please review and understand all installation manual instructions
before beginning installation. Many steps are sequential so it is
necessary to complete all elements as instructed.
Before proceeding, make sure that the unit is appropriate for your
particular brakes. The E/H 1000 produces 1000 psi, typically used
for duo-servo hydraulic drum brakes, while the E/H 1600 produces
1600 psi for most hydraulic disc brakes. Please refer to your brake
manufacturer for proper operating pressures.
2020.10 | 2

DX SERIES SERVICE MANUAL

ELECTRIC/HYDRAULIC ACTUATORS

Mounting consideration should be given to the following:
1.

The unit must be level, with the filler neck up.

2.

It is the responsibility of the installer to provide necessary
fasteners for attachment of the actuator to the trailer.

3.

Mount unit where it will not be submerged in water.

4.

Mounting near the hitch is preferred. Do not mount near the
trailer axles or rear of the trailer.

CAUTION

CAUTION
Always use new DOT 3, DOT 4, or DOT 5 brake fluid from a sealed
container. Never attempt to reuse old or dirty fluid. Do not overfill
the unit. Take care to protect painted surfaces from contact with
the brake fluid. Wash off any spilled brake fluid.
Mount the emergency breakaway switch and emergency breakaway
battery on the trailer, as detailed in the instruction sheets provided with
the emergency breakaway kit.

Bolt Mounting Pattern

The Dexter DX Series brake actuator contains sensitive electronics
that must be protected. Drilling additional holes in the housing,
electrostatically painting, or welding anywhere on the unit will
damage the unit making it inoperable and will void the manufacturer’s
warranty. Always remove the unit from the trailer before doing any
welding repair or modifications to the trailer structure.

9-13/16"
(250mm)

Connect the trailer brake lines to the actuator as follows:
1.

Remove the rubber or plastic plug from the 3/16” inverted flare
brake port.

2.

Brake line must be compatible with DOT 3, DOT 4, or DOT 5
brake fluid.

3.

4.

Flush existing brake system and lines until they are free of any
contaminants using DOT 3, DOT 4, or DOT 5 brake fluid prior to
connecting to the Dexter DX Series brake actuator.
Connect the brake line from the trailer brakes to the 3/16”
inverted flare fitting on the actuator. Do not tighten the 3/16”
brake line adapter more than the 22 Ft. Lbs. used at factory
installation.

CAUTION
Do not overfill fluid reservoir. Fluid will expand. Max fill level is
3/8” below bottom of filler neck.

2-1/2"
(63.5mm)

Electrical Wire Colors and Function

CAUTION
Only use a maintained battery with no less than 12.5v (see
battery chart below). Testing with a battery charger or other
device will cause loss of function.
% Battery Charge Chart
0%

10.5v
5”

.37

Air Gap

20%

40%

60%

80%

11.66v 11.96v 12.24v 12.5v

100%

12.73v

CAUTION
Undersized wire will increase electrical resistance and will prevent
proper operation of this unit.
BLACK – 30 amp 12 volt supply from tow vehicle*
BLUE – Output from electronic brake controller in tow vehicle
WHITE – Trailer and tow vehicle ground

Fill the unit with DOT 3, DOT 4, or DOT 5 brake fluid, while maintaining a
3/8” air gap below the filler neck.

DX SERIES SERVICE MANUAL
ELECTRIC/HYDRAULIC ACTUATORS

YELLOW – Cold side of breakaway switch
It is important that wire lengths for the BLACK power lead and WHITE
ground lead be no longer than 25 feet from the DX Series brake
actuator to the supply power (i.e. on board trailer battery or the tow
2020.10 | 3

Electrical Schematic
Trailer
Plug
BLUE
BLACK
WHITE

+12 Volt
40 Amp
Circuit From
Tow Vehicle
Ground From
Tow Vehicle

ORANGE/BLACK

Charger
Breakaway
Battery
12 Volt
9 Amp Hour
Minimum

BLUE

YELLOW

Connect
To The
Trailer
Ground
Circuit

vehicle battery). The DX Series brake actuator needs to be located as
close as possible to the battery near the front of the trailer. DO NOT
mount the DX Series brake actuator near the trailer axles or rear of
the trailer. Having the wire length longer than 25 feet may cause issues
with performance and the normal operation of the unit.
It is critical that the BLACK power lead and WHITE ground lead from
the tow vehicle to the input of the actuator are sized and properly
terminated (i.e. dedicated 30-40* amp circuit on the tow vehicle – 12
gauge wire minimum). 10-gauge wire is recommended to optimize
performance. Consult the SAE wiring guidelines for proper trailer
electrical harness design.
*Low temperature applications below 0°F require a 40-amp circuit.
The blue wire from the electric brake controller is connected through
the trailer plug to the blue wire on the actuator. The yellow wire from
the DX Series brake actuator is connected to the cold side of the trailer
emergency breakaway switch. Under no circumstances should the
actuator blue wire and the DX Series brake actuator yellow wire be
connected together, nor should the blue wire ever be grounded.
The white wire is connected to the trailer ground and also connected
to the tow vehicle ground through the trailer plug. The black wire is
connected to the +12V power line from the tow vehicle. The black wire
can also be connected to large on‑board batteries. The black wire
is connected to the small breakaway battery only through the black
wire on the charger of the breakaway battery. When connecting and
disconnecting the black wire, sparking may occur. This is a normal
occurrence.

2020.10 | 4

Hydraulic
Line

LIGHT
BLUE/
YELLOW

BreakAway
Switch

BLACK

ADAPTER
058-036-00
(IF REQUIRED)

WHITE

BLACK

Lanyard

WHITE

From Tow
Vehicle Controller
(Typically Blue)

Note: Either an onboard or breakaway
battery may be used.

Electrical Installation Requirements
Requires an Electric Brake Controller – The Dexter DX Series brake
actuator is intended to be used with an electric brake controller in the
tow vehicle. The unit will operate with a wide variety of controllers but
provides optimum performance when used with a Dexter electric brake
controller . The electric brake controller must have an output capacity of at
least 5 amps for proper operation of the Dexter DX Series brake actuator.
Although compatible, time based brake controllers are not recommended.

CAUTION
It is the responsibility of the end user to ensure that their electric
brake controller is compatible with the Dexter DX Series brake
actuator. Dexter attempts to provide compatibility with most
controllers available, but is unable to anticipate design changes
that might be introduced by the various controller manufacturers.
Electrical Connections – Make sure all electrical connections are
clean, dry, weather tight, and secure to prevent damage to the wiring
from dragging or becoming entangled with foreign objects. A dedicated
ground connection between the tow vehicle and trailer is also required.
Breakaway Battery Requirement – To comply with federal
requirements, the trailer must be equipped with a breakaway switch and
battery. The breakaway battery needs to have a minimum capacity of 9
amp hours and needs to be maintained in a fully charged condition at
all times. The breakaway battery should be checked for proper charge
level before every use.

DX SERIES SERVICE MANUAL

ELECTRIC/HYDRAULIC ACTUATORS

Charging the Breakaway Battery – The breakaway battery must be
kept fully charged at all times in order to function properly. Use only
those breakaway battery kits that include a charging device. Do not
attempt to charge the breakaway battery directly from the tow vehicle
without the appropriate charging device.

Test Electrical Operation
1.

Attach the trailer to the towing vehicle. Do not connect trailer
plug to tow vehicle until step #2 is completed.

2.

Pull the breakaway switch. The Dexter DX Series brake actuator
should run. If the unit does not run, check breakaway battery
condition and system wiring. Reset the breakaway switch, which
will turn the unit off. Note: When the unit is running, the motor
will generate a “hum” that changes pitch as the unit builds
pressure. This is normal.

3.

Connect trailer plug to tow vehicle.

4.

Turn the ignition switch on and turn the electric brake controller
on. Inertia type controllers will often require the vehicle to be
moving in order for the Dexter DX Series brake actuator to
come on by means of the brake pedal. If the unit does not run,
check system wiring.

5.

Apply the controller manual slide. The Dexter DX Series brake
actuator should run and brake lights come on.

!

CAUTION

Testing the Dexter DX Series brake actuator confirms that it is
operating. It DOES NOT confirm that the brakes are operating
properly. Regular inspection, adjustment, and maintenance of
the brakes, lines, hoses, drums, discs, fluid, and other associated
components is necessary to ensure proper brake operation.
6.

7.

Some brake controllers will not produce a high enough signal
voltage to actuate the trailer brakes when the vehicle is at a
standstill. Minimal trailer brake force is produced when the
controller voltage output to the DX Series brake actuator is at
least 3 VDC. Maximum trailer brake force is achieved at 12 VDC
on the actuator blue wire.
When the tow vehicle brakes are released, the unit may
continue to run for a few seconds.

Bleeding and Brake Adjustment
1.

It typically is much easier to bleed the brakes with two people
working together.

2.

Special care must be taken to insure that the Dexter DX Series
brake actuator does not run out of brake fluid. Check the fluid
level frequently during the bleeding process.

3.

Block the wheels on the trailer and towing vehicle.

DX SERIES SERVICE MANUAL
ELECTRIC/HYDRAULIC ACTUATORS

4.

If the trailer is equipped with drum brakes, check that the brake
running clearances are properly adjusted consistent with the
trailer manufacturer’s recommendations.

CAUTION
Failure to properly adjust the brakes on trailers equipped with drum
brakes can result in slower response time of the Dexter DX Series
brake actuator.
5.

Install plastic tubing onto the bleeder screw of the wheel
cylinder/caliper farthest from the Dexter DX Series brake
actuator. If towed vehicle has multiple axles, always start with
the rear axle first.

6.

Immerse the free end of the plastic tube in a clean clear
container partially filled with brake fluid.

7.

Open the bleeder screw one half turn on the wheel cylinder/
caliper.

8.

To activate the Dexter DX Series brake actuator, turn the ignition