Roadmaster 98300 Installation Instructions Manual - Troubleshooting
Troubleshooting
continued from preceding page
all connections are airtight.
4. If the towing vehicle is a Ford Class C motorhome,
the proportioning valve must be teed into the front hy-
draulic brake line — the rear brake line does not supply
sufficient hydraulic pressure.
5. Not all of the air was bled from the brakes after
installing the proportioning valve. Re-bleed the propor-
tioning valve, as well as all brakes (and any compo-
nents connected to the braking system) downstream
from the brake tee.
Symptom
The BrakeMaster air cylinder will extend and de-
press the towed vehicle’s brake pedal. However, it
will not retract when the motorhome brake pedal is
released.
Solution
1. Make certain that the air cylinder has been installed
directly in line with the brake pedal. If it is mounted at
an angle to the brake pedal (to one side or the other),
the air cylinder may jam in the extended position.
2. Dirt or debris can enter the air lines if the weather
covers are not used over the quick couplers. It may
accumulate at the quick exhaust valve on the air cyl-
inder, preventing the valve from venting air out of the
air cylinder. Disassemble the quick exhaust valve and
make certain it is not jammed.
3. If a system of diodes was used to wire the towed
vehicle’s lights for towing, make certain that a diode
is installed at every point where the motorhome brake
light wire connects to the towed vehicle’s brake light
wire.
When the air cylinder extends and depresses the
towed vehicle’s brake pedal, it energizes the towed
vehicle’s brake light wire. If diodes are not installed in
the circuit, current will travel back to the motorhome
and activate the BrakeMaster solenoid.
As long as the solenoid is activated, it will not allow
air to vent from the air cylinder — the air cylinder will
remain extended.
Symptom
The towed vehicle brakes abruptly the first time
BrakeMaster is activated, ‘flat spotting’ the tires. Also,
after towing, there may be excessive brake dust on the
wheels of the towed vehicle, and/or an unusual odor
near the towed vehicle’s brakes.
Solution
1. The stored vacuum in the towed vehicle’s power
brake system must be depleted before towing — pump
the brake pedal several times. Depending on the make
and model of the towed vehicle, it may be necessary
to pump the brake pedal repeatedly.
Deplete the vacuum in the power brakes every time
the towed vehicle’s engine has been started — typically,
when the vehicle is connected for towing.
The engines in some vehicles, such as the Saturn
Vue, must be started periodically during towing. If the
towed vehicle’s engine must be started periodically,
always deplete the vacuum in the vehicle’s power brake
system before you resume towing.
Refer to the caution statement on page 15.
2. If the towed vehicle has an ‘active’ (or, ‘continuous
power assist’) braking system, order the optional brake
pressure reducer (part number 900002) to adapt the
vehicle to the BrakeMaster system.
Vehicles with ‘active’ brake systems include several
hybrid vehicles, such as the Ford Escape hybrid and
the Mercury Mariner hybrid, as well as the H3 Hum-
mer. These vehicles, and others with ‘active’ braking
systems, are designed so that even when the ignition
is turned to the ‘tow’ position, the braking system is still
active.
If the reducer is not installed, BrakeMaster will apply
excessive force to the towed vehicle’s brake pedal.
3. If the towed vehicle does not have power brakes,
order the optional brake pressure reducer (part num-
ber 900002) to adapt the vehicle to the BrakeMaster
system.
BrakeMaster is designed to work with vehicles that
have a power brake system (even though the power
brakes are not activated while towing).
If the reducer is not installed, BrakeMaster will apply
excessive force to the towed vehicle’s brake pedal.
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