Power Distribution Module: Description and Operation
POWER DISTRIBUTIONThis group covers the various standard and optional power distribution components used on this model. 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 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 aftermarket 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)
- Fuse Block
- Accessory power outlet
- Micro Relay Bank
Following are general descriptions of the major components in the power distribution system. Refer to the owner's manual for more information on the features, use and operation of all of the power distribution system components.
FUSE BLOCK
An electrical Fuse Block is located in the left endcap of the instrument panel.
The left instrument panel endcap is a snap-fit fuse access cover that conceals the fuse block and 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 fuse block.
All of the current entering and leaving the fuse block does so through wire harnesses, which are connected to the fuse block. The fuse block houses blade-type fuses. Internal connection of all the fuse block circuits is accomplished by an intricate network of hard wiring and bus bars. For complete circuit diagrams, refer to the appropriate wiring information. The wiring information includes wiring diagrams, proper wire and connector repair procedures, further details on wire harness routing and retention, as well as pin-out and location views for the various wire harness connectors, splices and grounds.
The fuses and circuit breakers are available for service replacement. The fuse block unit cannot be repaired and is only serviced with the instrument panel wiring harness assembly. If any internal circuit or the fuse block is faulty or damaged, the entire instrument panel wire harness and fuse block assembly must be replaced.
IOD FUSE
All vehicles are equipped with an Ignition-Off Draw (IOD) fuse that is disconnected within the Fuse Block when the vehicle is shipped from the factory. Dealer personnel are to reconnect the IOD fuse in the Fuse Block as part of the preparation procedures performed just prior to new vehicle delivery.
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, including the clock. 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 Fuse Block cavity 4 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 serves no useful purpose to the dealer technician in the service or diagnosis of any vehicle system or condition, other than the same purpose as that of any other standard circuit protection device.
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, tbe battery should be tested and recharged at regular intervals during the vehicle storage period to prevent the battery from becoming discharged or damaged. Refer to Battery for the location of additional service information covering the battery.
MICRO RELAY BANK
A relay bank is located behind and above the glove box. It holds six micro relays and blade-type automatic resetting circuit breakers.
All of the current entering and leaving the micro relay bank does so through wire harnesses, which are connected to the micro relay bank. The relay bank houses six blade-type automatic resetting circuit breakers. Internal connection of all the micro relay bank circuits is accomplished by an intricate network of hard wiring and bus bars. For complete circuit diagrams, refer to the appropriate wiring information. The wiring information includes wiring diagrams, proper wire and connector repair procedures, further details on wire harness routing and retention, as well as pin-out and location views for the various wire harness connectors, splices and grounds.
The circuit breakers are available for service replacement. The micro relay bank cannot be repaired and is only serviced with the instrument panel wiring harness assembly. If any internal circuit or the relay bank is faulty or damaged, the entire instrument panel wire harness must be replaced.
POWER DISTRIBUTION CENTER (PDC)
All of the electrical current distributed throughout this vehicle is directed through the standard equipment Power Distribution Center (PDC). The molded plastic PDC housing is located in the left side of the engine compartment, below and to the outboard side of the master cylinder. 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.
All of the PDC outputs are through the integral engine compartment wire harness.
The PDC houses up to nine maxi-fuses. The PDC also houses up to ten mini-fuses, up to four full International Standards Organization (ISO) relays, and up to eight ISO micro-relays. Internal connection of all the PDC circuits is accomplished by an intricate network of hard wiring and bus bars. For complete circuit diagrams, refer to the appropriate wiring information. The wiring information includes wiring diagrams, proper wire and connector repair procedures, further details on wire harness routing and retention, as well as pin-out and location views for the various wire harness connectors, splices and grounds.
The fusib]e link, 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.