Auto Electrical Works Paper 2, May/June 2015

Question 2

Fig. 1 is the circuit diagram of a system in a motor vehicle.

(a)        Identify the:
            (i)         system in Fig. 1;
            (ii)        partslabelled X, Y and Z.

(b) Table 2 contains some faults associated with the system in Fig. 1.
Table 2

	Fault	One effect on the operation of the system	One possible remedy
(i)	Low specific gravity of electrolyte
(ii)	Poor battery earthing
(iii)	Worn out ring gear
(iv)	Partial contact of key when closed
(v)	Worn out pinion gear

Complete Table 2.

Observation

(a)        (i)         Starting system

                        (ii)        X – solenoid switch
                                    Y – flywheel
                                    Z – starter motor

(b) Table 2

	*Fault*	*One effect on the operation of the system*	*One possible remedy*
(i)	Low specific gravity of electrolyte	Low battery voltage Damage to battery cell Low cranking ability	Recharge battery Replace electrolyte and recharge Change battery
(ii)	Poor battery earthing	Slow cranking No cranking Solenoid not actuating	Remove, clean and fix cable Replace cable if faulty
(iii)	Worn-out ring gear	Noisy operation No cranking Damage of pinion	Replace ring gear Replace flywheel
(iv)	Partial contact of key when closed	Slow cranking No cranking	Change ignition switch Clean contact
(v)	Worn-out pinion gear	Noisy operation Damage to flywheel ring-gear	Change pinion

The report by the Chief Examiner indicated that majority of the candidates wrongly identified the diagram as charging system instead ofstarting system as required in question 2(a)(i)while the part labelled Y was named by many as ring gear as against the flywheel. The report further stated that a large percentage of the candidates that attempted the question did not respond well to the ‘b’ part.

Auto Electrical Works Paper 2, WASSCE (SC), 2019

Question 2

Observation