Amperage Checks; Resistance Checks; Contactor And Contactor Coil Checks - Yale 524150797 Maintenance Manual

ELECTRICAL SYSTEM
YES- Proceed to Step 6.
NO- Verify TS04 and TS05 terminal connections.
Refer to ELECTRICAL SYSTEM 2200YRM1508
for battery disconnect switch checks.
6. Measure continuity of Fuse FU2.
Is resistance <1 ohm?
YES- Proceed to Step 7.
NO- Replace Fuse FU2.
7. Measure resistance between key switch terminals
TS04 and TS05.
Is resistance <1 ohm?
YES- Inspect CPS 01 socket 1 for appropriate
crimping in terminals. Inspect voltage between
CPS01 socket 1 and B(-) to be same as battery
voltage. If not, inspect circuit 010 for excessive re-
sistance, damage, loose, or open connections.
NO- Inspect key switch terminals to be appropri-
ately connected. If connections are clean and se-
cure and resistance is ≥1 ohm, replace key switch.

Amperage Checks

An ammeter is used to measure amperage or current
flow through a circuit. An ampere is the measurement
of electron flow, which can be used to measure the
amount of electrons that are flowing through a circuit.
Ohm's Law states that current flow in a circuit is equal
to the circuit voltage divided by total circuit resistance,
known as the potential difference. Since amperage is
the current in the circuit, increasing voltage also in-
creases the current, or amperage levels.
Measuring amperage is always performed by placing
the ammeter in series with the device or circuit. This
will cause all current to flow through the protected me-
ter. The circuit must be operating in order to measure
amperage. Never measure amperage on high amper-
age circuits or in parallel to a circuit, this can result in
the damage of the meter and the electrical system.

Resistance Checks

The ohmmeter is used to measure a circuit or device's
resistance in ohms. Ohmmeters use low internal volt-
age and current which flow through an isolated circuit
or device being tested. The voltage of the meter bat-
tery and the amount of current flow in the circuit are
Check the Service Manual section in Yale Axcess Online for possible updates and check pertinent Bulletins
General Maintenance and Diagnostic Data
used to calculate the circuit's resistance. It is neces-
sary to disconnect or isolate the circuit being test so
not to damage the vehicle's electrical system or the
ohmmeter.
An ohmmeter is used to perform:
• Resistance of a load device
• Resistance of conductors
• Value of resistors
• Operation of variable resistors
• CANbus termination resistors
• Continuity

Contactor and Contactor Coil Checks

1. Measure voltage between the coil's positive termi-
nal and B(-).
NOTE: Key in ON position.
Is voltage same as truck's battery voltage?
YES- Proceed to Step 2.
NO- Inspect the Coil's battery B(+) input circuit for
open or short.
2. Disconnect coil's ground control circuit. Measure
resistance between ground circuit terminal and
B(-).
NOTE: Actuate coil ground control to determine if
controller is sending activation signal to coil.
Is resistance <1 ohm?
YES- Proceed to Step 3.
NO- Inspect ground control circuit. Verify that control-
ler is receiving device input signal.
3. Measure battery voltage between main contac-
tor's battery B(+) terminal and B(-).
NOTE: Key in ON position.
Is voltage same as truck's battery voltage?
YES- Repair or replace faulty contactor.
NO- Inspect main contactor battery cable for loose,
damaged, or corroded connections.
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