1. Disconnect the wiring lead (1) from the glow plug (2) after turning the main switch off.
2. Turn the main switch key to the “PREHEAT” position, and measure the voltage between the lead terminal and the chassis.
3. Turn the main switch key to the “START” position, and measure the voltage between the lead terminal and the chassis.
4. If the voltage at either position differs from the battery voltage, the wiring harness or main switch is faulty.
