Electrical System

Electrical Power Distribution

Electrical power distribution provides battery power to the electrical and electronic systems. See Fig. 3.1 for power distribution component locations.
The following components make up the power distribution system:
MEGA Fuse Junction Block (MFJB), EPA07 only
Powertrain Power Distribution Module (PT-PDM)
  • 1. SAM Cab
  • 2. Powertrain PDM (PT-PDM)
  • 3. Powernet Distribution Box (PNDB)
  • 4. SAM Chassis
  • 5. Main Ground Junction Block
  • 6. MEGA Fuse Junction Block
  • 7. Cab Load Disconnect Switch (optional location)
  • 8. Cab Load Disconnect Switch (optional location)
  • 9. Trailer PDM
Fig. 3.1, Component Locations
Powernet Distribution Box (PNDB), EPA10 and newer
Cab Load Disconnect Switch
Auxiliary PDM

MEGA Fuse Junction Block, EPA07

On EPA07 vehicles, the MFJB distributes battery power to the alternator, SAM cab, SAM chassis, and powertrain PDM. Battery power may also be routed to an inverter and a trailer PDM. The MFJB houses up to five MEGA fuses, and is located on the left frame rail in front of the batteries. See Fig. 3.2 .
  • 1. MEGA Fuse Junction Block
  • 2. Main Ground Junction Block
Fig. 3.2, EPA07 MEGA Fuse Junction Block

Powernet Distribution Box, EPA10 and Newer

The PNDB distributes battery power to the SAM cab, SAM chassis, powertrain PDM, and other keep-alive circuits.
The PNDB is mounted in the engine compartment on the frontwall near the steering column. The label on the PNDB fuse cover identifies typical circuits. See Fig. 3.3 .
  • 1. Powertrain PDM (PT-PDM)
  • 2. Inline Fuse, Auxiliary PDM
  • 3. SAM Chassis
  • 4. Powernet Distribution Box (PNDB)
Fig. 3.3, Engine Compartment Power Distribution Components

Power Distribution Modules

Powertrain PDM

The powertrain PDM contains fuses and relays that provide battery and ignition power to the engine, aftertreatment device, transmission, and other powertrain-related circuits. It is mounted in the engine compartment, above the driver-side inner fender.

Auxiliary PDM

The optional auxiliary PDM is used when additional circuit protection is needed for optional features. For example, if a beacon light is added to the Cascadia, it may require an auxiliary PDM. The auxiliary PDM may contain fuses and relays for these devices. It is mounted in the cab, behind the doghouse cover.

Trailer PDM

The optional trailer PDM, mounted on the frame rail, is used to supply trailer power to the chassis-mounted trailer receptacles. The SAM chassis supplies control signals to the relays in the trailer PDM.

SAM Cab

The SAM cab is located behind the glove box inside the vehicle cab. See Fig. 3.4 . The SAM cab contains fuses and relays in addition to solid state circuit protection devices that will trip when a circuit is overloaded.
Refer to Chapter 25 for fuse and relay locations.
Fig. 3.4, SAM Cab Location

SAM Chassis

The SAM Chassis is located in the engine compartment on the driver-side frontwall. See Fig. 3.3 . The SAM chassis contains fuses and relays in addition to solid state circuit protection devices that will trip when a circuit is overloaded.
Refer to Chapter 25 for fuse and relay locations.

Circuit Protection Features

The SAM chassis and SAM cab may be equipped with self-resetting circuit breakers instead of fuses. Self-resetting circuit breakers are tripped when they reach 170°F (77°C), then self-reset once the temperature drops sufficiently. When the circuit overload is removed, this circuit protection will self-reset. Some of these circuits require the ignition switch to be cycled off then back on again for the self-reset to occur.
Some ECU's are equipped with a self-resetting circuit breaker removal tool.
WARNING
Always wear heat-protective gloves when handling a self-resetting circuit breakers, which can reach extremely high temperatures. Failure to use appropriate heat protection can lead to serious injury.
NOTICE
Self-resetting circuit breakers can be permanently damaged if improperly handled. Use the guidelines below to handle them safely.
Disconnect the batteries before removing a self-resetting circuit breaker.
Use a circuit breaker removal tool to remove a self-resetting circuit breaker. See Fig. 3.5 . Use of any other tool, including pliers, may damage the circuit breaker.
  • 1. Circuit Breaker Removal Tool
  • 2. Self-Resetting Circuit Breaker
Fig. 3.5, Self-Resetting Circuit Breaker Removal
Never attempt to probe a self-resetting circuit breaker while installed on the SAM Cab or SAM Chassis. Remove the circuit breaker first, or use a non-contact infrared thermometer to measure temperature.

Cab Load Disconnect Switch

WARNING
Turning the cab load disconnect switch (CLDS) to the off position does not disconnect the connection between the battery and the starter. To work on the vehicle safely, the negative leads must be disconnected from the battery.
IMPORTANT: The ignition should be turned off before turning the CLDS to on or off.
The CLDS is used to avoid excessive draw on the battery when the vehicle is parked for an extended period of time by disconnecting (or opening) the connection between the battery and the most of the vehicle electrical system.
The CLDS may be mounted:
inside the cab on the outboard side of the driver's seat;
at the battery box;
outboard on the left frame rail.
See Fig. 3.6 for an EPA07 CLDS; see Fig. 3.7 for an EPA10 and newer switch.
Fig. 3.6, Cab Load Disconnect Switch, EPA07
Fig. 3.7, Cab Load Disconnect Switch, EPA10 and Newer
If the CLDS is turned to the off position while the vehicle is running, the emergency power system will activate. The powertrain PDM will receive power from the emergency power feed, but the batteries will not be charging. See the Emergency Power Supply heading below for details.

Emergency Power Supply

The Cascadia electrical system has an emergency power circuit that supplies battery power for exterior lighting. This assists vehicle visibility in the event a MEGA fuse is open circuit. The emergency power circuit is live even when the CLDS is turned off.
The emergency power supply feature allows for the vehicle to be driven off the highway and for the exterior lighting to remain on in the event of a SAM Cab or SAM Chassis failure. The emergency power supply will cause certain exterior lamps to flash (depending on if it is the SAM Cab or SAM Chassis that failed), indicating that the vehicle is disabled.

SAM Cab Fault

If the emergency power supply system activates, do not shut down the engine until the vehicle is in a safe position to do so. It will not be able to be restarted until the problem is corrected. If emergency power mode is due to a SAM Cab fault, the gauges will become unresponsive but the engine will remain running until it is turned off.
When the ignition is in the ON position, the emergency power supply will cause the following lamps to flash:
dash panel lights
clearance lights
front marker lights
side marker lights
trailer taillights
rear stop lights

SAM Chassis Fault

The engine may be able to be restarted when the SAM Chassis fails. When the ignition is in the ON position, the emergency power supply will cause the following lamps to flash:
dash panel lights
identification lights
front marker lights
turn-signal indicators in the ICU (alternately)
side marker lights
rear turn-signal lights
trailer taillights
If the ignition switch is turned ON while the load disconnect switch is in the OFF position, the emergency power supply feature will activate the following lamps:
clearance lights (flashing)
side marker lamps (flashing)
low beam headlights

Progressive Low Voltage Disconnect

Progressive low voltage disconnect (PLVD) shuts off electrical power to selected circuits based on the battery voltage, ignition switch position, and engine running status. There are three groups of circuits with increasing levels of priority for disconnect. PLVD stays at each level for a minimum amount of time to prevent rapid cycling between levels. When PLVD changes its level, the battery voltage may raise slightly due to the reduced load.
When battery voltage drops below a predetermined value, loads designated as comfort loads (priority level I) are shut down first. Then loads designated as house loads (priority level II) are shut down. If necessary, basic loads (priority level III) are shut down last.
PLVD allows the driver to continue using critical loads, while noncritical loads are temporarily unavailable. Calculations for disconnecting loads are based on battery voltage, ignition switch status, and engine rpm. Also, a time delay is implemented for the shutdown and reactivation of loads to avoid unnecessary cycling of loads when battery voltage is close to shutdown thresholds.
One minute before the comfort loads or house loads are shut down, the alarm in the instrument cluster beeps. No alarm sounds before basic loads are shut down.
If the interior lights have been shut down by PLVD, pressing one of the interior light switches (if equipped) brings the interior lights back on.
NOTE: It is possible to charge a cell phone in an emergency when the truck batteries are low. 12V power receptacles in the main dashboard remain powered in order for cell phone charging during a low voltage emergency.
  • 1. 12V Power Receptacles
Fig. 3.8, 12V Power Receptacle, Main Dashboard
CAUTION
Do not use emergency cell phone charging regularly, This will damage the PLVD strategy for startability during low voltage.
See Table 3.1 for the type of loads shut down under specific conditions.
See Table 3.2 for the loads that are designated comfort, house, and basic load status.
Type of Loads Shut Down Under Specific Conditions
Key Switch Position
Engine On, Voltage less than 12.5 Volts
Engine Off, Voltage less than 12.3 Volts
Engine Off, Voltage less than 12.1 Volts
Off
N/A
Priority level I, II loads
Priority level I, II, and III loads
Accessory
N/A
Priority Level I loads
Priority level I, II loads
On
Priority level I loads
Priority Level I loads
Priority level I, II loads
Start
N/A
N/A
N/A
Table 3.1, Type of Loads Shut Down Under Specific Conditions
Designated Loads
Type of Load
Function
Priority Level I
12V power receptacle 6 (sleeper, refrigerator)
Amplifier power, accessory
General sleeper light
Foot well light
Reading light 1 (dimmer/theater)
Reading light 2 (dimmer/theater)
Rear baggage compartment light
12V power receptacle 5 (sleeper, cigar), battery
Auxiliary circulation fan-sleeper, battery
12V power receptacle 4 (sleeper, cigar), battery
Reading light 4 (switched locally), battery
Priority Level II
Heated seats, ignition*
Sleeper HVAC controller, accessory*
Cabin HVAC controller, accessory*
Radio, accessory (clamp 15R)
Power feed spare output I, battery
Power feed spare output III, battery
Mirror heating, passenger*
Mirror heating, driver*
Power feed spare output IV, battery
Power feed spare output II, battery
Fuel/water separator heater element, ignition*
Air dryer (pneumatic, electrically heated), accessory*
Auxiliary circulation fan-windshield, accessory*
Accessory heater power
Utility light
Utility light
Dome light rear
Area lighting (lower bunk and sleeper work surface), battery
Dome light cab, battery
Overhead compartment lights, battery
12V power receptacle 3 (sleeper, cigar), battery
Stand-alone HVAC, battery
Advertising light, accessory*
Dome light passenger
Dome light driver/forward overhead
Priority Level III
CB radio, battery†
Fleet management system, battery†
Trailer power, battery or ignition
12V power receptacle 2 (dash, phone), battery
12V power receptacle 1 (dash, cigar), battery
*  When the vehicle has Optimized Idle, these functions will not operate with the ignition switch in the accessory position. Optimized Idle may also turn these functions off to reduce stress on the batteries. Refer to the Optimized Idle section in Chapter 11 for more information.
†  May or may not shut down depending on how an additional parameter is set at the factory or dealership.
Table 3.2, Load Designation

Inverter/Charger

The optional Freedom HF Inverter/Charger powers small appliances and other electric equipment. It is located in the driver-side luggage compartment. See Fig. 3.9 . The unit has one three-pin GFIC OUT connector, one three-pin GFIC IN connector, and two AC power outlets.
There are three models available for the Cascadia:
1000W : 1000 watt, 20-amp
1500W : 1500 watt, 40-amp
1800W : 1800 watt, 40-amp
Fig. 3.9, Inverter/Charger
DANGER
Do not store gasoline, flammable material, or any component with a connection to the fuel system in the storage compartment with the inverter/charger. The unit contains equipment that may produce sparks. Storing flammable or electrical equipment in proximity to the unit could result in fire or explosion hazards, which could result in serious injury or death.
The display on the sleeper control panel provides information about the operation of the unit. See Fig. 3.10 . Refer to Table 3.3 for details on the display panel.
  • 1. Power
  • 2. LED Display
  • 3. Select
  • 4. Input Voltage LED
  • 5. Input Current LED
  • 6. Output Power LED
  • 7. Status LED
Fig. 3.10, Inverter/Charger Display Panel (1000W shown)
Display Panel Functions
Number
Name
Function
1
Power
Press the power button for one second to turn on the unit.
Press and hold the button for five seconds to enter the feature settings mode, then press the button to toggle between the following modes:
Charging Current Setting
Inverter Mode Setting
Alarm Setting
Shutdown Setting
Factory Setting
Refer to the owner's manual for more information.
2
LED Display
The LED display screen shows status information and fault codes.
3
Select
The Select button changes the display or settings.
Press the Select button to cycle through the setting options. Press and hold the Select button for five seconds to save the setting. Refer to the owner’s manual for more information.
In "Inverter Mode Setting" press the button to turn the inverter mode ON or OFF.
With the inverter mode ON, press the button to choose what appears on the LED display screen: Input Voltage, Input Current, or Output Power. Details are provided below.
NOTE: The unit is in "Inverter Mode" when shore power is not present and the unit is using the battery to power the appliances connected to it.
In an alarm condition, press and hold the button for two seconds to disable or enable the audible alarm.
In "Charging Current Setting" mode, press the button to select the charger current.
4
Input Voltage LED
In inverter mode, when Input Voltage is selected, the corresponding LED will light up and the display will show the input voltage.
5
Input Current LED
In inverter mode, when Input Current is selected, the corresponding LED will light up and the display will show the input current.
6
Output Power LED
In inverter mode, when Output Power is selected, the corresponding LED will light up and the display will show the output power.
7
Status
The Status indicator displays one of three colored lights that indicates the unit's mode of operation:
Green : Utility (Shore Power Mode)
A solid green light indicates that the battery is fully charged.
A flashing green light indicates that the unit is charging the battery.
Yellow : Battery (Inverter Mode)
A solid yellow light indicates that the unit is using the battery to supply AC power.
A flashing yellow light indicates that the unit is in inverter mode, but that AC shore power is detected and is transferring to shore power mode within 20 seconds.
Red : Fault Condition
The fault status light indicates a fault condition with the unit. Refer to the owner’s manual for fault code information and troubleshooting procedures.
Table 3.3, Display Panel Functions
For more information about troubleshooting, settings, and other features, refer to the owners manual included with the inverter/charger.