Taylor-Dunn B0-254-48 Operation, T Roubleshooting And Replacement Parts Manual page 164

Electrical Troubleshooting
Test 4. KEY FAULT
TEST 4.1:
Turn the key switch ON and place the forward and
reverse switch in the center OFF position
Perform the following tests:
Test the voltage at pin #1 on the 12 pin logic card
connector.
If the voltage equals battery volts, then skip
ahead to Test #5.
Test the voltage on both terminals of the battery
voltage positive circuit breaker (see below).
If the voltage on both terminals equals
battery volts, then skip ahead to test #4.2.
If the voltage on both terminals does not
equal battery volts, then check the circuit
breaker and wiring to the main circuit breaker
and to the batteries for open circuits.
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.
TEST 4.2:
Test the voltage at the hot terminal (red wire) on
the key switch.
If the voltage equals battery volts, then skip
ahead to test #4.3.
If the voltage does not equal battery volts,
then check the wiring from the key switch to
the battery voltage positive circuit breaker.
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.
Typical Circuit Breaker
Sevcon Troubleshooting
Page 10
TEST 4.3:
Test the voltage at the cold side (violet/black wire)
of the key switch.
If the voltage equals battery volts, then skip
ahead to test #4.4.
If the voltage does not equal battery volts,
then replace the key switch.
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.
TEST 4.4:
Check the wire from the cold side of the key switch
to pin #1 on the 12 pin logic card connector for
open circuits.
NOTE: Your vehicle may be equipped with a charger
interlock relay. The charger interlock relay
disables the control system when the
charger is connected to its power source.
The interlock relay contacts are in series with
the wire from the cold side of the key switch
to pin #1 on the 12 pin logic card connector.
The relay is located in the charger cabinet.
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.
STOP
Stop, do not continue. Reaching this point
indicates a failure in the Sevcon power unit
or an error was made during testing. Confirm
all previous tests were performed correctly
before replacing the Sevcon power unit.
After any repairs are made, completely retest
the vehicle before lowering the drive wheels to
the ground. Failure to retest the vehicle could
result in unexpected movement of the vehicle
resulting in injury or property damage.