Ignition Systems Flashcards
7 cards from real ASE practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Ignition Systems flashcards as text
What typically causes carbon tracking on a spark plug boot or ignition coil tower?
Answer: Compromised insulation allowing voltage to arc along the surface to ground
Carbon tracking results from high-voltage arcing along the surface of degraded insulation, depositing conductive carbon that creates a permanent low-resistance path causing misfires.
What is the primary function of the ignition control module (ICM)?
Answer: Switch primary coil current on and off to induce secondary high voltage
The ICM switches the primary coil circuit on and off based on PCM signals; when primary current is interrupted, the collapsing magnetic field induces high voltage in the secondary winding.
Which spark plug electrode material offers the longest service life in modern vehicles?
Answer: Platinum or iridium
Platinum and iridium have extremely high melting points and corrosion resistance, allowing extended service intervals of up to 60,000–100,000 miles.
Abnormally high secondary ignition circuit resistance most commonly indicates what condition?
Answer: Worn spark plug electrodes, a wide plug gap, or damaged spark plug wires
High secondary resistance is most often caused by worn plug electrodes with increased gaps, carbon/oil fouling, or deteriorated high-voltage spark plug wires.
In a distributor-less ignition (DIS) system, what does the camshaft position sensor determine?
Answer: Which cylinder is on its compression stroke to fire the correct coil
The camshaft position sensor provides cylinder identification — telling the PCM which cylinder is approaching TDC on compression so the correct coil is fired.
Engine knock (detonation) is most often caused by which ignition-related condition?
Answer: Excessively advanced ignition timing
Over-advanced timing fires the mixture too early, causing combustion pressure to peak before TDC and creating the pressure spikes heard as knock or detonation.
What is the typical recommended replacement interval for iridium spark plugs?
Answer: 60,000–100,000 miles
Iridium spark plugs are rated for 60,000 to 100,000 miles due to iridium's extreme hardness and high melting point, which dramatically slows electrode erosion.