Taylor-Dunn B0-254-48 Operation, T Roubleshooting And Replacement Parts Manual page 168

Electrical Troubleshooting
TEST 7.3:
If the vehicle does not travel in forward, skip ahead to
test #7.4.
Place the forward and reverse switch in the REVERSE
position.
Referencing battery positive, test the voltage at the White/Black
wire on the F&R switch.
If the voltage equals battery volts, skip ahead to test
#7.4.
If the voltage does not equal battery volts, then the F&R
switch has failed.
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 7.4:
Check the wires from the F&R switch to the logic card connector for continuity.
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.
Sevcon Troubleshooting
Page 14
This troubleshooting guide is written in
sequential order. All tests must be performed in
the order that they are written. Starting in the
middle or skipping sections when not instructed
to do so may lead to invalid test results.