Peterbilt Medium Duty Trucks Operator's Manual after 1-07

Preventive Maintenance
All the electrical circuits have fuses to protect them from a
short circuit or overload. If something electrical on your chassis
stops working, the first thing you should check for is a
blown fuse.
1. Turn OFF all lights and accessories and remove the ignition
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.
CAUTION: Follow all manufacturers’ circuit protection
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
Electrical System
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.
Batteries
WARNING! Battery posts, terminals, and related
accessories contain lead and lead compounds,
chemicals known to the State of California to
cause cancer and reproductive harm. Wash
hands after handling.
Battery Access
The vehicle is originally equipped with two batteries.
Replacement batteries must meet the following specifications:
maintenance-free, group 31 size, threaded stud, 12V/
650 cold cranking ampere (CCA), and 160 minutes of
reserve capacity. The battery compartment has space to
install an optional third battery.
Medium Duty (R10/06) Y53-6008 – 183 –