Electrical/Control Systems

Warning

Inspect and check the electrical system at regular intervals. Defects, such as loose connections or scorched cables must be repaired before using the machine.

Only use proper, original equipment fuses with the specified current rating. Turn off the machine immediately if there is any indication of a problem with the electrical system.

Disconnect the negative battery cables from the negative battery terminals, before performing electrical service or electrical welding on the machine.

Turn off all electrical equipment before connecting leads to the batteries, including electrical switches on the battery charger or jump-starting equipment.

When disconnecting at the battery terminals, remove the cable connected to the negative terminal first. When installing a battery, connect the positive terminal cable first.

Sparks and open flames can ignite explosive battery gas from incidental contact or static discharge. Turn off all switches and the engine when working on batteries. Keep battery terminals tight. Contact between a loose cable clamp and a terminal post can create an explosive spark.

Work on the electrical system must be performed only by a trained technician.

Electrical Schematics

Refer to the Schematics section in this manual, starting on page343, for electrical schematic information.

Battery

Refer to “Battery” on page 143 for detailed battery maintenance information.

Power Distribution

Electrical circuitry is protected from overloading and short circuits by a combination of fuses and relays contained in the power distribution modules located inside the engine compartment and the ROPS/FOPS (cab). Fuses protect electrical circuits and relays provide switched power to the circuits.

Refer to “Fuses and Relays” on page145 for fuse, relay and diode location and circuit rating and function information.

Power Distribution Module Fuse Socket Test

Warning

BEFORE beginning this service procedure, shut down the machine according to “Mandatory Safety Shutdown Procedure” on page22.

Using a volt/ohm multimeter or a test lamp, measure between test points and the chassis ground for 12V, with the wiring connected and power applied to the selected circuit. When the circuit is energized, 12V should be present on both sides of the fuse.