Taylor-Dunn B0-248-TT, Operation, T Roubleshooting And Replacement Parts Manual, Page: 148 / 204

Electrical Troubleshooting
Charger Troubleshooting Page 10
TESTING THE INTERLOCK RELAY
Operation
The Interlock Relay disables the vehicle from running whenever the charger is connected to a working AC
power source. When the charger is plugged in, the relay contacts open and break the Key Switch connection
to the speed controller. The Interlock Relay is available for built-in chargers only. Not all built-in chargers
are equipped with this relay. To identify chargers that are equipped with the Interlock Relay:
Inspect the charger wire harness where it enters the charger cabinet for two Violet/Black
wires. If these wires are present then the charger is equipped with the Interlock Relay.
Testing
6. Disconnect the charger from the AC power source.
7. Disconnect the two Violet/Black wires at the charger harness knife connectors.
8. Set the DMM to check for continuity and connect the DMM leads to the wires
going into the charger.
•
The DMM should indicate a closed circuit. If the DMM indicates an open circuit, then the relay
or the wires to the relay have failed. Stop here and repair the problem.
9. Connect the charger to a working AC power source.
•
The charger should turn on. If the charger does not turn on then their may be a problem with the
AC power source or the AC wiring to the charger. Refer to the beginning of this section for
charger troubleshooting. DO NOT continue until you have confirmed that the AC power source is
working.
•
The DMM should indicate an open circuit. If it still indicates a closed circuit, then the relay or the
wires to the relay have failed. Stop here and repair the problem.
•
If the DMM indicates an open circuit then the interlock relay is functioning normally.
1. Make sure the key-switch is in the “OFF” position, then remove the
key.
2. Place the forward-reverse switch in the center “OFF” position.
3. Set the park brake.
4. Place blocks under the front wheels to prevent vehicle movement.
5. Disconnect the main positive and negative cables at the batteries.
4. Disconnect the wires from the contact terminals on the timer relay.
5. Reconnect the batteries.
6. Wait 5 seconds, then test the continuity across the timer relay contact terminals.
•
If this is a closed circuit, then the timer start up circuit is functioning normally.
•
If there is an open circuit, then the timer relay has failed and the relay must be replaced.