OPERATOR'S MANUAL

Preventive Maintenance Electrical System
Medium Duty
(R05/09) Y53-6027 – 219 –
All the electrical circuits have fuses to protect them from a
short circuit or overload. If something electrical on your chas-
sis stops working, the first thing you should check for is a
blown fuse.
1. Turn OFF all lights and accessories and remove the igni-
tion key to avoid damaging the electrical system..
2. Determine from the chart on the fuse panel which fuse
controls that component.
3. Remove that fuse and see if it is blown.
4. If it is blown, replace it with a fuse of the same rating.
Adding Electrical Options
WARNING! Do not add a fuse with a rating
higher than 30 amps. Doing so may damage the
electrical system and cause a fire, possibly
causing death, personal injury or property dam-
age.
CAUTION: Follow all manufacturers’ circuit pro-
tection recommendations for the components
and wires being added.
Spare circuits are located throughout the wiring for the dash.
For proper electrical system performance, refer to a wiring
diagram for your chassis before adding electrical options.
Truck-Body Connection
Your vehicle includes a junction box mounted to the frame for
wiring the vehicle body to the main chassis harness.
Refer to the Body Builder's Manual for further information on
using the Truck and Body Connection.
Battery Cables
WARNING! Battery cables can cause fires result-
ing in death or serious personal injury and/or
property damage if not properly maintained and
located. Regularly inspect the battery cables
and connectors for damaged or compromised
cable insulation. Contact your Authorized Ser-
vice Center if you are in need of repairs or infor-
mation.
Turn off the ignition and disconnect the negative battery
cable.