404b Truck Electrical Circuit Service

Question 1

All electrical schematics are drawn in a de-energized condition and all the electrical
components are drawn in their:
a) closed position.
b) open position.
c) normal position.
d) non-normal position.

Answer 1

c) normal position.

Question 2

List the five (5) components every truck electrical circuit must contain to be safe and functional.

Answer 2

• voltage source
• electrical conductors
• control device
• overcurrent protection device
• load

Question 3

Ohm’s Law is used in calculating values in electrical circuits. E is the symbol for Electromotive force measured in volts (V), I is the symbol for Intensity of current flow, measured in amperes (A) and R is the symbol for Resistance to current flow, measured in ohms (Ω) What is the correct mathematical expression for Ohm’s Law?

a) E = I × R
b) I = E/R
c) R = E/I
d) all of the above

Answer 3

d) all of the above

Question 4

When you are troubleshooting a malfunctioning truck lighting circuit, you use a process of eliminating circuit components that are not causing a problem in order to find the circuit component that is causing the problem. This process is called:

a) calculating the electrical failure.
b) picking the electrical failure.
c) illuminating the electrical failure.
d) isolating the electrical failure.

Answer 4

d) isolating the electrical failure.

Question 5

High electrical resistances in electrical circuits will cause voltage drops. Voltage drops that occur in truck lighting systems will cause light bulbs to:

a) illuminate normally.
b) illuminate dimly.
c) illuminate brighter than normal.
d) burn out.

Answer 5

b) illuminate dimly.

Question 6

Manufacturers develop and publish _________ ___________ to guide you through troubleshooting procedures.

Answer 6

flow charts

Question 7

The electrical resistance values of all the components in the __________________ electrical circuit add together to form the total resistance value of the circuit.

Answer 7

series

Question 8

The current draw across each leg of a __________________ electrical circuit add together to form the total current draw for the entire circuit.

Answer 8

parallel

Question 9

An information ___________ _____________ allows the unit’s electronic control modules to communicate with each other.

Answer 9

data bus

Question 10

The best way to repair a broken wire going to the air bag inflator module is:

a) by using rosin core electrical solder.
b) by using a heat shrink butt end connector.
c) to never repair a wire in the air bag system.
d) to follow manufacturer’s procedure on SRS wiring repairs.

Answer 10

d) to follow manufactures procedure on SRS wiring repairs.

Question 11

When installing electrical accessories under the dash of the truck, make sure you do not splice into the:

a) red labelled wire harness.
b) blue labelled wire harness.
c) white labelled wire harness.
d) yellow labelled wire harness.

Answer 11

d) yellow labelled wire harness.

Question 12

To prevent any damage to the clockspring in the truck when removing a steering gear, you must ensure that:

a) you are familiar with the operation of the SRS system.
b) you have Centred the steering wheel before you disconnect the gear.
c) prevent the steering wheel from rotating while the gear is disconnected.
d) you perform all of the tasks listed above.

Answer 12

d) you perform all of the tasks listed above.

Question 13

What is installed in the connectors of an air bag circuit to help prevent accidental deployment?

a) locking mechanisms
b) shorting bars
c) gold plated pins and terminals
d) yellow labelling

Answer 13

b) shorting bars