Glow Plug System: Testing and Inspection

In a normally operating quick start system, when coolant temperature is below 122° F and the key is in the ``On'' position, the glow plug indicator turns on for about 3.5 seconds and the No. 1 Relay turns on for a few seconds.

RELAY NO. 1 AND GLOW INDICATOR ARE BOTH INOPERATIVE
1. Starter circuit fuse is burnt out or fusible link wire is open.
2. Starter wire circuit is open or not properly connected.
3. Controller defective or not properly connected.
4. Starter switch is inoperative.

RELAY NO. 1 INOPERATIVE
1. Relay No. 1 is open.
2. Relay coil in relay No. 1 is open.
3. Controller to No. 1 relay circuitry is open or not properly connected.
4. Grounding circuit for No. 1 relay is open or not properly connected.
5. Controller is inoperative.
6. Circuit from controller to signal feed wire of sensing resistor is open or not properly connected.
7. Terminals of sensing resistor are not connected.
8. Main terminal of No. 1 relay not connected.
9. Main contact open in No. 1 relay.
10. Terminals in quick preheat circuit not connected.
11. Engine harness ground not properly connected.
12. Quick preheating wiring not properly connected or circuit open.

GLOW INDICATOR LIGHT INOPERATIVE
1. Controller damaged.
2. Indicator circuit not properly connected or open.
3. Light bulb burnt out.

RELAY NO. 1 TURNS OFF WITHIN 2 SECONDS
1. Controller damaged.
2. One or more glow plugs defective.
3. Wiring at connector poorly connected.

RELAY NO. 1 WILL NOT TURN OFF AFTER A FEW SECONDS
1. Controller damaged.

RELAY NO. 1 OPERATES WHEN COOLANT TEMPERATURE IS ABOVE 122° F.
1. Thermostat switch is inoperative.
2. Short in circuit. In a normally operating quick start system, when coolant temperature is below 122° F and, the key held in the ``Start'' position, the glow plug indicator and the No. 2 relay will remain on until key is moved to ``On'' position.

RELAY NO. 2 AND GLOW INDICATOR INOPERATIVE
1. Starter switch ``R'' circuit not properly connected or open.

RELAY NO. 2 INOPERATIVE
1. Relay No. 2 terminals not connected.
2. Circuit between R terminal and No. 2 relay not properly connected or open.
3. No. 2 relay coil is open.

GLOW PLUG LIGHT REMAINS ON FOR 3.5 SECONDS AND CAUSES RELAY NO. 1 TO TURN ON
1. Thermo-switch circuit not properly connected or open.
2. Thermostat switch is inoperative.