Taylor-Dunn B0-T48-48 Taylor Truck T48, Operation, T Roubleshooting And Replacement Parts Manual

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Sevcon Troubleshooting
Page 16
Electrical Troubleshooting
Test 9. ELECTRIC MOTOR BRAKE
Description:
The electric motor brake is a 24-volt electromagnetic disc brake mounted between the drive motor
and the primary reduction gear case. The brake is controlled by the speed controller logic. At what
times the brake is applied or released is dependent on the controller programing and will vary
depending on the model vehicle.
Operation:
B+ is supplied to the brake when the key switch is turned on. When the control logic determines that
it is time to start, it provides B- at 24-volts through pin #9 on the logic card connector.
Testing:
Place the forward and reverse switch in the OFF
position, turn the key switch OFF.
Rotate the drive wheels to confirm the brake is
engaged.
If the brake is engaged then skip ahead to
9.1.
If the brake is not engaged then:
Disconnect the electric brake harness connector and
repeat the test.
If the brake is still not engaged then:
•
Remove the brake and repair or replace
the brake as required. Stop trouble shooting
here and repair the problem. When the
repair is completed, completely retest the
vehicle before lowering the drive wheels to
the ground.
If the brake engaged after the harness was
disconnected then:
Inspect the harness for shorts.
Stop troubleshooting here and repair the problem.
When the repair is completed, completely retest the
vehicle before lowering the drive wheels to the
ground.
Test 9.1
Close the seat switch, turn the key switch ON, place
the forward and reverse switch in the FORWARD
position, depress the accelerator pedal to engage
FS-1 only (creep speed).
Rotate the drive wheels to confirm the brake has
released.
If the brake released, then the brake system
is working and no further testing of the brake
is required.
If the brake did not release, then perform the
following tests:
Connect a volt meter from battery negative to the
Violet/Black wire at the electric brake harness plug.
If the voltage is less than battery volts then:
•
Check wiring to the key switch and continue
troubleshooting at test #4.2.
If the voltage equals battery volts then:
Connect a volt meter across the Violet/Black wire
and the Blue wire at the electric brake harness plug.
The voltage should start at approximately 24 volts,
then drop to approximately 15 volts after about 0.5
seconds.
If the test is good then:
•
The pigtail harness to the electric brake is
broken or the electric brake has failed.
Remove the brake and repair or replace
as required.
If the test is bad then:
The electric brake is part of the vehicle braking
system. Do not operate a vehicle with the
electric brake bypassed or disabled unless the
system is being tested for faults. Operating a
vehicle with the brake bypassed or disabled
may result in severe personal injury or property
damage.