Electrical Systems
Electrical System General Information
The Saf-T-Liner C2 uses an electrical system where multiple electrical signals are carried along a simplified set of wires, reducing the size of wiring bundles. There are significantly fewer wires overall, meaning less chance of damage, shorts, and other problems. The information in this chapter is to help familiarize the driver with the basic electrical system. Servicing the electrical system requires special skills and equipment and should only be performed by a qualified technician. Take the vehicle to an authorized Thomas Built Bus dealer when service is needed.
Power Distribution Modules
There are two power distribution modules (PDAs).
The main PDM is located under the hood on the driver's side above the fender. See Fig. 8.1 . The main PDM distributes battery power to the vehicle's control modules, and contains the fuses required to protect the power feed circuits to these modules. While the main PDM provides power to the modules, the modules themselves control power flow and circuit protection to the various components of the vehicle's electrical systems. Because of this, traditional PDM devices such as relays and circuit breakers are no longer necessary on the main PDM.
Inside the lid of the fuse box there is a sticker that shows the location of the fuses and describes the circuit(s) that each fuse protects. Fuse configuration will vary depending on the PDM assembly installed. See Fig. 8.2 . See Table 8.1 for descriptions of a typical set of fuses.
The cab PDM is located in the switch panel cavity at the driver's left elbow and handles circuits inside the vehicle, such as heaters, doors, fans, lights, and other interior accessories. See Fig. 8.3 .
Because the electrical system is multiplexed, no relays are needed. The multiplexing module performs the functions normally provided by relays.
Fuse Identification
|
||
---|---|---|
CAV
|
Description
|
Fuse
|
F1
|
VCU (spare)
|
10A (—)
|
F2
|
Blower Motor
|
30A
|
F3
|
Engine ECU
|
20A
|
F4
|
RR Wall HTR RLY LO/HI
|
30A
|
F5
|
Ignition Switch
|
10A
|
F6
|
Hydromax RLY (spare)
|
30A (—)
|
F7
|
Stepwell HTR RLY LO/HI
|
30A
|
F8
|
ICU3-M2
|
10A
|
F9
|
Transmission ECU
|
10A
|
F10
|
Expansion Module 1
|
30A
|
F11
|
Expansion Module 1
|
30A
|
F12
|
Radio/Diagnostic
|
20A
|
F13
|
Expansion Module 1
|
30A
|
F14
|
Expansion Module 2
|
30A
|
F15
|
Bulkhead Module
|
30A
|
F16
|
ABS ECU
|
15A
|
F17
|
Chassis Module
|
30A
|
F18
|
Bulkhead Module
|
30A
|
F19
|
Chassis Module
|
30A
|
F20
|
Bulkhead Module
|
30A
|
F21
|
Expansion Module 2
|
30A
|
F22
|
Bulkhead Module
|
30A
|
F23
|
Expansion Module 2
|
30A
|
F24
|
Hydraulic Pump and RLY (spare)
|
25A (—)
|
F25
|
Adjustable Pedals
|
10A
|
F26
|
Chassis Module
|
30A
|
F27
|
Heater Booster Pump
|
20A
|
F28
|
Bulkhead Module
|
30A
|
F29
|
Crossing Arm RLY
|
10A
|
- 1. Bulkhead Module
- 2. Main PDM
- 1. Battery Power Mega Fuse 1
- 2. Battery Power Mega Fuse 2
- 3. Engine Harness (green)
- 4. Forward Chassis Harness (blue)
- 5. Forward Chassis Harness (gray)
- 6. Frontwall Harness (black)