Parking Brake
Cable Frozen

Free Cable
and Lubricate

Improper Lining
Thickness or Location

Install New Shoes
and Linings

Dragging

-32-

SYMPTOM

No Brakes

CAUSES

REMEDIES

Broken or Kinked
Brake Line

Repair or Replace

Severe
Underadjustment

Adjust Brakes

Malfunctioning
Actuation System

Troubleshoot System

Brake Adjustment
Not Correct

Manual-Adjust Brakes
Automatic-Make Several
Reverse Stops

Excessively Worn
Brake Linings

Replace Shoe
and Lining

Incorrect Lining

Install Correct
Shoe and Lining

Grease or Fluid
Soaked Lining

Repair Grease Seal or
Wheel Cylinder. Install
New Shoe and Lining.

Frozen Master Cylinder
or Wheel Cylinder Pistons

Recondition or Replace
All Cylinders, Brake Fluid

Glazed Lining

Reburnish or Replace

Excessive Drum Wear

Replace

Trapped Air in Lines

Bleed System

Weak Brakes

Overloaded Trailer

Correct

Malfunctioning
Actuating System

Troubleshoot
System

Brake Adjustment
Not Correct

Manual-Adjust Brakes
Automatic-Make Several
Reverse Stops

Grease or Fluid
on Linings

Replace Shoes
and Linings

Grease or Oil
on Linings

Clean or Replace

Out of Round Drums or
Cracked Drums

Machine or Replace

Harsh Brakes

Surging Brakes

-33-

Braking Systems - Hydraulic

Troubleshooting

Electric/Hydraulic Troubleshooting Guide
Electrical Schematic
Trailer
Plug
Blue
Black
White

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

Orange/Black
Charger
Minimum
9 Amp Hour
Breakaway
Battery

Blue

Black

BreakAway
Switch

White

WHITE

BLACK

Lanyard

Light Blue/Yellow

From Tow
Vehicle Controller
(Typically Blue)

Hydraulic
Line

Yellow
Connect
To The
Trailer
Ground
Circuit

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

Braking Systems - Hydraulic

Brakes are slow to respond
1. Re-bleed the trailer brakes and actuator.
2. If the trailer is equipped with drum brakes, readjust the drum
brakes to the brake manufacture’s recommended running
clearance.
3. Slow response can be caused by trailer wiring that is too
small.
4. For trailers where the E/H unit is located less than 10 feet
from the tow vehicle, 12 gage wire is recommended for the
black and white wires between the tow vehicle and the E/H
unit. All other wires should be a minimum of 16 gauge.
5. For trailers where the E/H unit is located more than 10 feet
from the tow vehicle, 10 gage wire is recommended for the
black and white wires between the tow vehicle and the E/H
unit. All other wires should be a minimum of 16 gauge.
6. Slow response can be caused by improper adjustment
of the brake controller. On inertia-based electronic brake
controls, adjust the pendulum (inertia sensor) to a more
aggressive setting and/or increase the gain setting.

-34-

2. With the ignition switch on and the brakes not applied, you
should have 12-13 volts between the black and white wires
on the E/H unit.
3. Clean and replace the ground between the trailer and the
E/H unit.
4. Test operation of the unit using the breakaway test
procedure.
Breakaway test procedure - do not leave the breakaway
switch pulled for more than two minutes during any of the
steps outlined below
1. Pull the breakaway switch on the trailer.
2. If the unit runs and builds pressure, that indicates the
actuator is functioning properly. The problem most likely is
a defective electronic brake controller in the tow vehicle or
defective wiring between the tow vehicle and the E/H unit.
3. If the unit runs but will not build pressure, the problem most
likely is a defective solenoid valve in the E/H unit and the
actuator should be returned for repair.
4. If the unit still does not run after the breakaway battery is
fully charged, verify that the voltage between the white wire
and yellow wire is at least 12 volts.
5. If the voltage is less than 12 volts, either the breakaway
switch or the breakaway wiring is defective.
6. If the voltage is greater than 12 volts, the E/H unit should be
returned for repair.
Trailer brakes too aggressive
1. Reduce the gain setting on the in-cab electronic brake
controller.

-35-

Braking Systems - Hydraulic

Unit will not run when the ignition is on and the brake pedal
is depressed
1. Verify that the trailer and tow vehicle are wired as detailed
on the electrical schematic.

General Maintenance ‑ Hydraulic Brakes
Drum Brake Adjustment
Most Dexter 12¹⁄₄" hydraulic brakes have a self adjusting feature. If
manual adjusting is required, use the following procedure:
Brakes should be adjusted (1) after the first 200 miles of operation
when the brake shoes and drums have “seated,” (2) at 3,000 mile
intervals, (3) or as use and performance requires. The brakes
should be adjusted in the following manner:
1. Jack up trailer and secure on adequate capacity jack stands.
Follow trailer manufacturer’s recommendations for lifting and
supporting the unit. Make sure the wheel and drum rotates
freely.

!

CAUTION

Braking Systems - Hydraulic

Do not lift or support the trailer on any part of the axle
or suspension system. Never go under any trailer unless
it is properly supported on jack stands which have been
rated for the load. Improperly supported vehicles can
fall unexpectedly and cause serious injury or death.
2. Remove the adjusting hole cover from the adjusting slot on
the bottom of the brake backing plate.
3. With a screwdriver or standard adjusting tool, rotate the star
wheel of the adjuster assembly to expand the brake shoes.
Adjust the brake shoes out until the pressure of the linings
against the drum makes the wheel very difficult to turn.
4. Then rotate the star wheel in the opposite direction until the
wheel turns freely with a slight lining drag.
5. Replace the adjusting hole cover and lower the wheel to the
ground.
6. Repeat the above procedure on all brakes. For best results,
the brakes should all be set at the same clearance.

-36-

Wheel Cylinders
Inspect for leaks and smooth operation. Clean with brake cleaner
and flush with fresh brake fluid. Hone or replace as necessary.

Brake Lines
Check for cracks, kinks, or blockage. Flush with fresh brake fluid.
Bleed system to remove all air. Use DOT3 or DOT4 brake fluid,
and replace as necessary.

Shoes and Linings
A simple visual inspection of your brake linings will tell if they are
usable. Replacement is necessary if the lining is worn (to within
¹⁄₁₆" or less), contaminated with grease or oil, or abnormally scored
or gouged. Hairline heat cracks are normal in bonded linings and
should not be cause for concern. When replacement is necessary,
it is important to replace both shoes on each brake and both
brakes of the same axle. This will help retain the “balance” of your
brakes.

!

CAUTION

POTENTIAL ASBESTOS DUST HAZARD!
Some older brake linings may contain asbestos dust,
which has been linked to serious or fatal illnesses.
Certain precautions need to be taken when servicing
brakes:
1. Avoid creating or breathing dust.
2. Avoid machining, filing or grinding the brake linings.
3. Do not use compressed air or dry brushing for
cleaning (dust can be removed with a damp brush).

-37-

Braking Systems - Hydraulic

Most of the brake components are very similar to those used in
electric brakes, and maintenance is comparable for the hub and
drum, shoes and linings, and bearings. Specific maintenance
activities are as follows:

After replacement of brake shoes and linings, the brakes must
be re-burnished to seat in the new components. This should be
done by applying the brakes 20 to 30 times from an initial speed
of 40 m.p.h., slowing the vehicle to 20 m.p.h. Allow ample time for
brakes to cool between applications. This procedure allows the
brake shoes to seat in to the drum surface.

Hardware
Check all hardware. Check shoe return spring, hold down springs,
and adjuster springs for stretch or wear. Replace as required.
Service kits are available.

Instructions for 10-12K
Hydraulic Disc Brakes
Notice to Buyer
It is recommended that all brakes be replaced at the same time to
ensure balanced braking performance.

Braking Systems - Hydraulic

Preparation
1. Jack up trailer and secure on adequate capacity jack stands.
Follow trailer manufacturers recommendations for lifting and
supporting the unit.

!

CAUTION

Do not lift or support the trailer on any part of the axle
or suspension system. Never go under any trailer unless
it is properly supported on jack stands which have been
rated for the load. Improperly supported vehicles can fall
unexpectedly and cause serious injury or death.
2. Remove the wheel from the hub, leaving the brake exposed.
Removal of Old Brake Caliper
1. With tire-wheel assembly(s) removed from hub and zero
pressure in hydraulic system, remove hex nuts from
slider bolts and withdraw bolts from brake assembly. Note
orientation of anti-rattle springs. Lift calipers from assembly
and secure to prevent damage to brake hose. Do not allow
caliper to hang from the hose. Remove anti-rattle springs
and brake pad.
-38-

2. Rotor-inspect for grooves, flaking, cracks, heat checking,
excessive thickness variation, insufficient overall rotor
thickness and overall width (measurement from inboard
rotor face to rotor mounting surface). Machine or replace as
necessary.
3. Rotor Specifications:
Rotor Thickness
10-12K

1.185 New, 1.12 Min. Service Limit

Rotor Thickness
#14 Torflex®

2.15 New, 2.09 Service Limit

Rotor Overall Width

3.655 New, 3.59 Service Limit

Lateral Runout

.003 T.I.R., .010 T.I.R. Maximum

Thickness Variation

.0008

Hub and Rotor Removal and Installation
1. With hubcap removed and oil drained, straighten locking
tabs on tang washer and remove outer locknut, tang washer,
inner locknut, bearing washer, and outer bearing. Remove
hub and rotor assembly.
Note: A puller may be required due to unitized seal press
fit on spindle. Remove inner bearing and seal. Service
bearings as necessary.
2. Prior to reassembly, ensure that the hub bearing housing
is clean. Reinstall inner bearing. Coat the O.D. of a new
seal with a bore sealant (Permatex or equivalent) prior to
installation.
3. Mount hub and rotor assembly on spindle and install outer
bearing, bearing washer, and inner bearing nut.

-39-

Braking Systems - Hydraulic

Inspection
1. Slider bolts must be straight and free of rust pits, missing
chrome, or cracks in the chrome plating. Replace if
necessary. Anchor yoke bores must be free of corrosion and
excessive wear. O-Rings must be free from nicks and cuts.
Replace as necessary. Caliper assembly must be free of
fluid leaks and torn or deteriorated dust boots and O-Rings.
Repair as required.

4. Tighten inner nut to 100 Ft. Lbs. while turning hub to seat
bearings.
5. Loosen nut to remove pre-load torque. Hand tighten nut,
then back off ¹⁄₈ turn minimum, ¹⁄₄ turn maximum.
6. Install tab washer and outer locknut. Torque locknut to
100‑175 Ft. Lbs. Ensure that the inner nut does not rotate.
Bend 2 tabs over flat on outer locknut to secure.
7. Install hub cap and add oil to hub. Capacity is 2.5 oz. of SAE
90W gear oil.
Installation
1. Installation is reverse of disassembly. Use appropriate tools
and methods to retract caliper pistons sufficiently to reinstall
caliper over the new pads. Caliper and anchor yoke O-Rings
should be lubricated with a light film of high temperature
brake lubricant prior to slider bolt installations. Slider bolts
should be installed from the outboard side of the caliper.
Ensure the anti-rattle springs are located properly.

Braking Systems - Hydraulic

2. Use extreme care when installing the slider bolts to prevent
damage to the O-Rings. Installation tool #071-182-00
threaded onto the slider bolts is recommended.
3. DO NOT FORCE OR HAMMER BOLTS IN. Secure slider
bolts with new locknut. Actuate brakes numerous times to
remove excess pad clearance prior to operation of vehicle.
Torque Specifications:
Slider Bolts Locknuts

15-25 Ft. Lbs.

Anchor Yoke Mounting Nuts

45-55 Ft. Lbs.

Bleeder Screw

9-12 Ft. Lbs.

Rotor Mounting Nuts 10K-12K
Rotor Mounting Bolts #14 Torflex
Outer Spindle Nuts

85-95 Ft. Lbs.
®

90-110 Ft. Lbs.
100-175 Ft. Lbs.

Hub Cap

20-30 Ft. Lbs.

Wheel Mounting Nuts
(with clamp ring)

-40-

200 Ft. Lbs.

Item

Description

Qty/
Brake

10K, 12K

1

Anchor Yoke Assembly 10K-12K
(includes 6 of item #6)

1

090-002-02

1

Anchor Yoke Assembly #14 Torflex®
(includes 6 of item #6)

1

090-011-02

2

Caliper Assembly
(includes items #6, 3, 9, 10)

1

089-002-02

3

Caliper Piston

2

054-066-00

12

Shoulder Screw ⁵⁄₈ x 5

2

007-186-00

13

Hex Screw ⁷⁄₁₆-20 x 1.75

7

007-116-00

14

Flange Nut

8

006-046-00

15

Hex Nut ⁷⁄₁₆-20