The engine starter motor cranks slowly and then fails to crank. What is the most likely cause and how is it diagnosed?

A. Most likely: flat or weak starting battery. Diagnose: multimeter at battery terminals — resting voltage below 12.0V indicates discharged state; voltage drops below 9.5V under cranking = battery cannot deliver starting current. Also check: battery terminals clean and tight (resistance at terminals causes voltage drop); battery isolator switch position; starter solenoid click heard when key is turned

B. Slow cranking is normal in cold weather — continue cranking for up to 5 minutes

C. Slow cranking indicates low engine oil — top up immediately before starting

D. If the starter cranks at all the battery is fine — the fault is in the engine management system

A. Compression ignition: diesel fuel is ignited by the heat of highly compressed air (compression ratio ~22:1) — no spark plugs are used. Fuel is injected into the compressed air at the moment of ignition

B. Diesel engines work at lower compression ratios than petrol engines for safety

C. Diesel engines use spark plugs but fire in a different sequence to petrol engines

D. Diesel engines use carburettors to mix fuel and air before compression

A. Compression, ignition, induction, exhaust — the compression happens before air enters

B. Induction (air in): piston down, air drawn into cylinder. Compression: piston up, air compressed to high temperature. Power (ignition): fuel injected, combustion drives piston down. Exhaust: piston up, exhaust gases expelled

C. Ignition, compression, induction, exhaust

D. Induction, power, compression, exhaust