A heavy-duty truck operating in Northern Ontario frequently experiences cold starts. The technician observes that the glow plug indicator light on the dash flickers and the engine cranks slowly but eventually starts after several attempts. Which of the following is the MOST likely cause of this issue?

Question: A heavy-duty truck operating in Northern Ontario frequently experiences cold starts. The technician observes that the glow plug indicator light on the dash flickers and the engine cranks slowly but eventually starts after several attempts. Which of the following is the MOST likely cause of this issue?

Answer options: ✅ High resistance in the glow plug circuit, possibly due to corroded connections.

• A faulty engine coolant temperature sensor providing an incorrect cold reading.
• The glow plug control module is programmed for an incorrect voltage output.
• An open circuit in one of the glow plugs, causing others to draw too much current.

Correct answer: High resistance in the glow plug circuit, possibly due to corroded connections.

Explanation: Flickering glow plug indicator and slow cranking often signify high resistance in the glow plug circuit. Corroded connections or wiring can impede current flow to the glow plugs, reducing their effectiveness and increasing the load on the battery during cranking. This aligns with common cold-start issues on heavy equipment.