• | Test the relay circuit for voltage with the relay removed. Use a voltmeter to inspect for system voltage at cavities B and 30. Cavity 30 is hot at all times. Cavity B is energized by the engine control switch. |
• | Use an ohmmeter to test cavities A and 31. Cavity A is the ground side for the relay. Cavity 31 is the load side, glow plugs, of the relay. |
• | The relays load side can be inspected for high resistance with an ohmmeter. The reading should be 0.1 ohm or less. If the resistance is higher, replace the relay. |