Power Circuit Function
To provide unswitched power to primary components and switched power to secondary components whenever the battery is connected.
The power circuits are divided among the unswitched power circuits, switched power circuits (key switch in RUN or START position), and secondary power circuits. The secondary power circuits become active when switched power circuits energize those components that in turn provide current paths for the secondary circuits. A majority of the secondary power circuits are governed by the logic contained within the instrument control cluster.
Power Circuit Operating Conditions, Unswitched Circuits
Voltage must be present at the following components with the key switch in the OFF position:
– Battery Positive Terminal
– Starting Motor Battery Terminal
– Key Switch, Terminal B
– Alternator, Terminal B
– Glow Plug Relay, Terminal 30
– Fuel Shutoff Relay, Terminal 30
– Light Switch, Terminal B
– Power Port, Center Terminal (if equipped)
– Instrument Control Cluster, Terminal J1-B
The positive battery cable connects the battery to the starting motor. The starting motor bolt is used as the 12 VDC tie point for the rest of the electrical system.
Protection of the unswitched circuits is provided by two fuse links and three fuses.
Open, loose, or corroded connections compromise the integrity of the entire electrical system. Ground cable connections are as equally important as their positive cable counterparts.
Open, loose, or corroded connections compromise the integrity of the entire electrical system. Ground cable connections are as equally important as their positive cable counterparts.
Power Circuit Operating Conditions, Switched Circuits
In addition to the unswitched circuits, voltage must be present at the following components with the key switch in the RUN position, transmission in neutral, and PTO switch OFF:
– Key switch terminal L to Fuse F8
From Fuse F8, the 562 Red-series of switched power wires lead to the:
– MBR Switch
– Neutral Switch
– Park Brake Switch
– PTO Switch
– Turn Signal Switch
– Seat Switch
– Fuel Pump
– Alternator, Connector pin 2
– Instrument Control Cluster, Terminal J1-A
