Basic Electrical Troubleshooting; Electrical Checks; Voltage Checks - Yale 524150797 Maintenance Manual

General Maintenance and Diagnostic Data

ELECTRICAL CHECKS

The following electrical checks are used to diagnose
circuit and component faults on trucks. Review the fol-
lowing information so that it may be applied when di-
agnosing a fault or status code.

Voltage Checks

Voltage is electrical pressure or force that pushes cur-
rent through a circuit. The force is measured in volts.
Low voltage to a load device will cause the device to
be inoperative or operate poorly. This can be caused
by a low battery source, high circuit resistance, poor
connections, or an open circuit; the resistance of poor
connections or poor ground acts as an additional load
in the circuit, causing low voltage pushing current, or
amperage, through a device.
A voltmeter is used to perform:
• Measurement of force
• Presence of voltage
• Voltage drops
When using a voltmeter to determine if voltage is
present and capable of operating a device, connect
the positive meter lead to the power circuit of a de-
vice's connector and connect the negative meter lead
to the negative battery terminal.
Measuring the voltage drop is performed by connect-
ing the positive test lead to the positive side of the de-
vice while simultaneously connecting the negative
meter lead to the negative side of the device. The test
can also be performed across a section of wire that is
faulty and suspected of having excessive resistance.
A voltage drop must be performed while the device is
operating. In a circuit with a single load device, the
device will drop the total voltage of the circuit. If the
device drops less than battery voltage, it can be as-
sumed that the circuits are using the remaining volt-
age as a source of excessive resistance or a poor
connection exists, assuming the battery state-of-
charge is correct.
1. Verify battery connectors for loose terminals and
appropriate crimping. Measure voltage between
terminal before FU1 and B(-).
NOTE: Key in ON position.
Check the Service Manual section in Yale Axcess Online for possible updates and check pertinent Bulletins
9030-03-4

Basic Electrical Troubleshooting

Is voltage 24 ± 2.5 Vdc?
YES- Proceed to Step 3.
NO- Disconnect battery and proceed to Step 2.
2. Measure resistance between truck frame and
each of the following test points:
• Battery postivie wire after FU1
• B(+) and B(-)
• U-Phase cable
• V-Phase cable
• W-Phase cable
• Pump positive cable
• Pump negative cable
Is resistance ≥1M ohm?
YES- Charge battery, perform battery maintenance,
for non-maintenance free batteries, read battery Spe-
cific Gravity level to be within manufacturer specifica-
tion.
NO- Inspect for all cable insualtion throughout the
truck. Inspect battery corrosion around terminals for
proper crimping.
3. Measure battery voltage between terminal after
FU1 and B(-).
NOTE: Key in ON position.
Is voltage 24 ± 2.5 Vdc?
YES- Proceed to Step 5.
NO-Proceed to Step 4.
4. Measure continuity of Fuse FU1.
Is resistance <1 ohm?
YES- Proceed to Step 5.
NO- Replace Fuse FU1.
5. Ensure battery disconnect switch in UP position,
measure voltage between TS04 and B(-).
Is voltage same as battery voltage?
ELECTRICAL SYSTEM