Power and Ground Distribution: Description and Operation

POWER DISTRIBUTION
All of the electrical current distributed throughout this vehicle (except for police package wiring used with rear fuse block) is directed through the standard equipment Power Distribution Center (PDC). The molded plastic PDC housing is located in the left front corner of the engine compartment, just in front of the coolant reservoir bottle. The PDC housing has a molded plastic cover. The PDC cover is easily removed for service access and has a convenient fuse and relay layout label affixed to the inside surface of the cover to ensure proper component identification. The PDC housing is secured in the engine compartment by one screw to the rear of the PDC and two clips on the front side. A small molded plastic protective cover on the front right side of the engine compartment is unsnapped to access the battery/generator cable input connection studs.

Included in the police package is an additional rear fuse block and remote rear power post.

The rear fuse block is located in the right corner of the trunk behind the trunk trim panel. The rear fuse block houses 2 relays and three fuses. The wiring is routed to an area just below the instrument panel in a six cavity connector to provide three fused ignition feeds. Three fused battery feeds in the PDC also are provided to the center stack area of the instrument panel within the same six cavity connector.

Only the police package has both fused ignition and battery circuits below the instrument panel. Special service vehicles have only the three fused battery circuits in the six cavity connector.

The remote rear power post is located in the right corner of the trunk side panel.

CAUTION: DO NOT USE THE REMOTE REAR POWER POST AS A REMOTE JUMP POST. SERIOUS DAMAGE CAN OCCUR. REFER TO LUBRICATION AND MAINTENANCE, JUMP STARTING FOR PROPER JUMP STARTING PROCEDURES.

The rear fuse block and the remote power post are serviced as part of the body harness.

POWER DISTRIBUTION SYSTEM
The power distribution system for this vehicle is designed to provide safe, reliable, centralized and convenient to access distribution of the electrical current required to operate all of the many standard and optional factory-installed electrical and electronic powertrain, chassis, safety comfort and convenience systems. At the same time, these systems were designed to provide centralized locations for conducting diagnosis of faulty circuits, and for sourcing the additional current requirements of many after market vehicle accessory and convenience items.

These power distribution systems also incorporate various types of circuit control and protection features, including:
- Fuses
- Fuse cartridges
- Fusible links
- Automatic resetting circuit breakers
- Relays
- Flashers
- Timers
- Circuit splice blocks

The power distribution system for this vehicle consists of the following components:
- Power Distribution Center (PDC)
- Junction Block (JB)
- Accessory power outlet

NOTE: DO NOT ATTEMPT TO SWAP POWER DISTRIBUTION CENTERS (PDC) FROM ONE VEHICLE TO ANOTHER. MOST OF THESE ASSEMBLIES ARE VEHICLE FEATURE SPECIFIC AND THEREFORE NOT INTERCHANGEABLE. ALWAYS USE THE CORRECT PART NUMBERED ASSEMBLY WHEN DIAGNOSING OR REPLACING A PDC.

CIGAR LIGHTER/POWER OUTLET
The power feed to the Cigar Lighter/Power Outlet can be HOT (12V - B+) with the ignition ON, or HOT (12V - B+) with the ignition OFF.

To change the operating mode of the Cigar Lighten Power Outlet, (Refer to ELECTRICAL/POWER DISTRIBUTION - STANDARD PROCEDURE).

IOD FUSE
All vehicles are equipped with an Ignition-Off Draw (IOD) fuse that is disconnected within the Junction Block when the vehicle is shipped from the factory. Dealer personnel are to reconnect the IOD fuse in the junction block as part of the preparation procedures performed just prior to new vehicle delivery

On left hand drive vehicles, the left end of the instrument panel cover has a snap-fit fuse access panel that can be removed to provide service access to the fuses in the junction block. On right hand drive vehicles the junction block is mounted on the right hand side of the instrument panel. A finger recess is molded into the access panel for easy removal. An adhesive-backed fuse layout map is secured to the instrument panel side of the access panel to ensure proper fuse identification. The IOD fuse is a 15 ampere mini blade-type fuse, located in fuse cavity # 34. The fuse is secured within a White molded plastic fuse holder and puller unit that serves both as a tool for disconnecting and reconnecting the fuse in its junction block cavity, and as a fuse holder that conveniently stores the fuse in the same junction block cavity after it has been disconnected.

Circuits Included With IOD Fuse
- Cluster
- Body Control Module
- Diagnostic Connector
- Map Lamps
- Glove Box Lamp
- Courtesy Lamps
- Compass Mini-Trip Computer
- Radio

The term ignition-off draw identifies a normal condition where power is being drained from the battery with the ignition switch in the OFF position. The IOD fuse feeds the memory and sleep mode functions for some of the electronic modules in the vehicle as well as various other accessories that require battery current when the ignition switch is in the OFF position. The only reason the IOD fuse is disconnected is to reduce the normal IOD of the vehicle electrical system during new vehicle transportation and pre-delivery storage to reduce battery depletion, while still allowing vehicle operation so that the vehicle can be loaded, unloaded and moved as needed by both vehicle transportation company and dealer personnel.

The IOD fuse is disconnected from JB fuse cavity # 34 when the vehicle is shipped from the assembly plant. Dealer personnel must reconnect the IOD fuse when the vehicle is being prepared for delivery in order to restore full electrical system operation. Once the vehicle is prepared for delivery, the IOD function of this fuse becomes transparent and the fuse that has been assigned the IOD designation becomes only another Fused B(+) circuit fuse.

The IOD fuse can be used by the vehicle owner as a convenient means of reducing battery depletion when a vehicle is to be stored for periods not to exceed about thirty days. However, it must be remembered that disconnecting the IOD fuse will not eliminate IOD, but only reduce this normal condition. If a vehicle will be stored for more than about thirty days, the battery negative cable should be disconnected to eliminate normal IOD; and, the battery should be tested and recharged at regular intervals during the vehicle storage period to prevent the battery from becoming discharged or damaged.

Fig. 4 Junction Block Location:

JUNCTION BLOCK
An electrical Junction Block (JB) is located in the left endcap of the instrument panel (Fig. 4). The JB combines the functions previously provided by a separate fuseblock module and relay center. It also serves to simplify and centralize numerous electrical components, as well as to distribute electrical current to many of the accessory systems in the vehicle. It eliminates the need for numerous splice connections and serves in place of a bulkhead connector between many of the engine compartment, instrument panel, and body wire harnesses.

The JB is positioned on a mounting bracket up and under the left instrument panel. It is secured by four screws. The JB is concealed behind the left instrument panel endcap. The left instrument panel endcap is a snap-fit fuse access cover that conceals the JB fuses. A fuse puller and spare fuse holders are located on the back of the endcap, as well as the fuse layout to ensure proper fuse identification. The left instrument panel endcap must be removed to access components other than the fuses in the JB.

All of the current entering and leaving the JB does so through wire harnesses, which are connected to the JB through integral connector receptacles molded into the JB housing. The JB houses blade-type fuses, blade-type automatic resetting circuit breakers, full International Standards Organization (ISO) relays, and ISO micro-relays. Internal connection of all the JB circuits is accomplished by an intricate network of hard wiring and bus bars. Refer to the appropriate wiring information. The wiring information includes wiring diagrams, proper wire and connector repair procedures, details of wire harness routing and retention, connector pin-out information and location views for the various wire harness connectors, splices and grounds.

The fuses, circuit breakers, relays, and are available for service replacement. The JB unit cannot be repaired and is only serviced as an assembly. If any internal circuit or the JB housing is faulty or damaged, the entire Junction Block assembly must be replaced.

Fig. 5 Power Distribution Center Location:

POWER DISTRIBUTION CENTER
All of the electrical current distributed throughout this vehicle is directed through the standard equipment Power Distribution Center (PDC) (Fig. 5). The molded plastic PDC housing is located in the left front corner of the engine compartment, just in front of the coolant reservoir bottle. The PDC housing has a molded plastic cover. The PDC cover is easily removed for service access and has a convenient fuse and relay layout label affixed to the inside surface of the cover to ensure proper component identification. The PDC housing is secured in the engine compartment by one screw to the rear of the PDC and two clips on the front side. A small molded plastic protective cover on the front right side of the engine compartment is unsnapped to access the battery/generator cable input connection studs.

All of the PDC outputs are through the integral engine compartment wire harness, which exits from the front of the PDC housing.

All of the current from the battery/generator cable connection enters the PDC through a 140 ampere fusible link that is secured with screws just inside the left end of the PDC housing. The PDC houses up to fourteen maxi-fuse cartridges, which replace all inline fusible links. The PDC also houses up to six blade-type fuses, up to four full International Standards Organization (ISO) relays, and up to seven ISO micro-relays. Internal connection of all the PDC circuits is accomplished by an intricate network of hard wiring and bus bars. Refer to the appropriate wiring information. The wiring information includes wiring diagrams, proper wire and connector repair procedures, details of wire harness routing and retention, connector pin-out information and location views for the various wire harness connectors, splices and grounds.

The fusible link, fuse cartridges, fuses and relays are available for service replacement. The PDC unit cannot be repaired and is only serviced as a unit with the engine compartment wire harness. If the PDC is faulty or damaged, the engine compartment wire harness assembly must be replaced.