Auto Electrical Works Paper 3, May/June 2022

Question 2

Fig. 3 is the diagram of the instrument panel on the dash board of a motor vehicle.

(i) Identify the units labeled P, Q, R and S.
(ii) State the symptom of fault that can be indicated by symbols T, U, V, W and X.

If M and N blink simultaneously and continually, what does this indicate?

Table 2 contains some symptoms of fault in the auxiliary system of a motor vehicle. Complete it by stating two possible causes of each of the symptoms given.

Table 2

S/N	Symptom of fault	Possible causes
(i)	Horn honks continually after a single push

(ii)	Wiper blade does not oscillate when switched ON

Fig. 4 is the diagram of a starting system.

(i) State:
I. the type of starting system in Fig. 4;
II. one reason for your answer in 2 (c) (i)I;
III. one other type of starting system apart from the one illustrated in Fig.4.

(ii) Table 3 contains some components of the system in Fig. 4. Complete it by stating one
function and symptom of fault of each of the components illustrated in Fig.4.
Table 3

Component	Function in system	Symptom of fault
Battery
Solenoid
Starter motor

The expected responses were:

(i) The units labeled P, Q,R and S in Fig. 3

P – Fuel level/guage indicator
Q – Speedometer
R – Tachometer
S – Water temperature guage/indicator

(ii) The symptom of fault that can be indicated by symbols T, U, V, W and X
T – low oil pressure
U – check engine
V – battery/charging system problem
W – tyre pressure problem
X – fog light is on

(iii) The M and N blink simultaneously and continually indicates

Hazard/take caution/emergency

Table 2

S/N	Symptom of fault	Possible causes
(i)	Horn honks continually after a single push	Faulty relay Partial contact Faulty switch Short circuit
(ii)	Wiper blade does not oscillate when switched ON	Faulty switch Blown fuse Disconnected linkage Faulty wiper motor

(i) I. The type of starting system in Figure 4

– inertia starter system
II. The reason for your answer in 2(c)(i)I

Solenoid is not fixed/mounted on the starter motor

III. Mention another type of starting system apart from the in Figure 4

Pre-engaged starter system

(ii)
Table 3

S/N

Component

Function in system

Symptom of fault

Battery

Feeds/supply voltage to the solenoid

No clicking sound in solenoid

Solenoid

Twitching of current from the battery motor

No clicking sound in solenoid
No output seen when terminal are tested

III

Starter motor

Converts the electrical energy from the battery to mechanical energy to drive the fly wheel

Noisy operation
No cranking
Low cranking speed

Questions 2 required candidates to show an understanding of the starting system and show familiarity with the different component parts and functions. The Chief Examiner reported that majority of the candidates showed only little knowledge of the starting system of a motor vehicle.

Auto Electrical Works Paper 3, WASSCE (SC), 2022