The cylinder 1 glow plug circuit delivers high-amperage current from the battery to the plug. This circuit starts at the glow plug controller or relay. It runs through the engine harness to the connector terminal on the plug. The engine computer monitors circuit resistance. If it detects an open circuit, short to ground, or high resistance, it sets a fault code. Corroded terminals or a damaged wiring harness are common points of failure in this circuit.
Mechanic Glossary
1 Glow Plug Circuit
The electrical pathway, including wiring, relays, and controller connections, that supplies current to the cylinder 1 glow plug.
Frequently Asked Questions
A loose wiring connector, a corroded terminal at the glow plug, or a break in the power wire leading to cylinder 1.
Use a test light or multimeter. Verify that 12 volts are delivered to the cylinder 1 harness connector when the ignition key is cycled to the run position.
Not necessarily. The code points to the wiring or electrical path. However, a burnt-out glow plug can trigger a circuit code due to infinite resistance.