Modern Truck Electrical Systems - Chapter 15

Practice flashcards covering Allison transmissions, Eaton AMTs, ABS/ATC functionality, hydraulic power brakes, and hybrid truck electrical systems.

In the context of Allison World Transmissions, what does the acronym WTEC stand for?

World Transmission Electronic Controls

How does an Allison World Transmission (WT) ECU determine when to shift?

It uses full authority control, meaning the transmission only shifts when commanded by the transmission ECU.

What are the three variable reluctance speed sensors used in the Allison World Transmission?

1. Engine 2. Turbine 3. Tail shaft (Output)

What specific type of troubleshooting software is used for Allison World Transmissions?

Allison Diagnostic Optimized Connection (DOCTM)

What is the difference between Eaton AutoShift and Eaton UltraShift systems?

Eaton AutoShift is a three-pedal system, while Eaton UltraShift is a two-pedal system.

What is the name of the private J1939 network used for communication between the driver interface and the Eaton transmission ECU?

The EPL

What PC-based electronic service tool (EST) is used to diagnose Eaton automated manual transmissions (AMT)?

Eaton ServiceRanger™

What is the standard tooth count for a typical ABS tone wheel?

100 teeth

In an air ABS system, what is a 'chuff test'?

A brief actuation of the modulation coil at start-up.

Why must traction control be disabled if a truck is being operated on a dynamometer?

Differential braking can cause the truck to drive off if only one drive axle wheel end is lifted or if wheel speeds differ significantly while the driveline is operated.

What does VORAD stand for in advanced ABS features?

Vehicle onboard radar

According to FMVSS 121, what color must the ABS warning lamp be?

Amber

Which pin on the J560 trailer socket provides power to the trailer ABS?

Pin 7

What technique is used by trailer ABS ECUs to signal a fault to the truck instrument panel without extra wiring?

PLC (Power Line Carrier)

For Hydraulic Power Brakes (HPB), what is the normal operating pressure maintained in the accumulator?

Approximately $2320\,psi$

At what pressure threshold does the low pressure warning lamp illuminate in an HPB system?

Below $1523\,psi$

What is the meaning of the acronym SAHR in hydraulic brake systems?

Spring-Applied Hydraulically Released parking brake

In a J1939 bus-type network, what is the resistance value for each of the two terminating resistors?

$$120\,\Omega$$

What is the primary difference between a parallel hybrid and a series hybrid truck?

In a parallel system, the internal combustion engine is supplemented by an electric motor; in a series system, the truck is propelled only by the electric motor while the engine acts as a generator to charge batteries.

What color insulation is used to identify high-voltage wiring in hybrid electric vehicles?

Orange

What is the purpose of an Electronic On-Board Recorder (EOBR)?

It serves as an electronic log book to record the hours of service (HOS) for truck operators.