Taylor-Dunn B0-248-TT, Operation, T Roubleshooting And Replacement Parts Manual, Page: 117 / 204

Maintenance, Service, and Repair
Electrical Troubleshooting
Page 7
These test procedures must be
performed in the order they were
written. If the test result is good,
then proceed to the next test or go
to the next section. Failure to do so
may result in incorrect test results.
Forward/Reverse Switch (48 Volt System)
The forward\reverse switch (F/R) is a double pole double throw center off
switch (DPDT). One pole controls the direction of the vehicle and the other
pole provides the Key Switch Input (KSI) to the speed controller. These two
poles have different functions and are isolated but a failure in either pole can
result in similar symptoms.
A typical DPDT switch is shown in the illustration to the right.
Terminal 1a is the common for one pole and 2a is the common for the other
pole. Terminals (b) or (c) will be connected to common (a) depending on how
the switch is activated.
Wires colored Green/Black, Blue/Black, and White/Black will be connected to
one pole, and Violet/Black will be connected to the other pole.
Turn the key switch ON, place the F/R switch in the center OFF position and depress the throttle pedal.
> Green/Black wire should be Control Volts.
> Violet/Black wire on common (a) should be Control Volts.
> All others should be LOW.
If Green/Black wire terminal is LOW, go to Throttle Module.
If Violet/Black wire terminal is LOW, check wiring to the key switch.
If any other terminal is Control Volts, then check the F/R switch and wiring for shorts.
Turn start switch ON, select FORWARD direction and depress the throttle pedal.
> Violet/Black wire on (a) and (b) should be Control Volts.
> Blue/Black wire should be Control Volts.
If Blue/Black wire terminal is LOW, replace the F/R switch.
If either Violet/Black wire terminal is LOW, replace the F/R switch..
If any other terminal is Control Volts, then check the F/R switch and wiring for shorts.
Turn start switch ON, select REVERSE direction and depress the throttle pedal.
> Violet/Black wire on (a) and (b) should be Control Volts.
> White/Black wire should be Control Volts.
If White/Black wire terminal is LOW, replace the F/R switch.
If either Violet/Black wire terminal is LOW, replace the F/R switch..
If any other terminal is Control Volts, then check the F/R switch and wiring for shorts.
If all above tests are good, then check wiring from F/R switch to the control panel