Diagnosis of Preheat Problems

ENGINE COOLANT TEMPERATURE BELOW 0~C (32~F)

PROBLEM POSSIBLE CAUSE CORRECTION

Glow Plug Relay Will 1. Bad connection between the 1. Check the fusible link between the
Not Turn On battery and the relay. starter and the glow plug relay. Check
the wiring and connections from the battery to the starter and to the relay.
2. Worn relay. 2. Check the relay for continuity. Refer to "Component Inspection."
3. Worn engine control switch. 3. Check the switch operation and connections.
4. Fuse #5 blown in engine control 4. Check the fuse in the fuse block behind switch circuit. the lower right instrument panel.
5. Disconnected circuit between the 5. Check the wiring and connectors. relay and the timer.
6. Timer not grounded. 6. Check the timer ground.
7. Worn timer. 7. Check the timer Refer to "Component Inspection."
8. Thermal switch stuck closed. 8. Check the switch. Refer to "Component Inspection."

Glow Plug Relay 1. Poor fusible link connection. 1. Check the fusible link connections be-
Turns On, But Glow tween the starter and relay, and wiring
Plugs Fail To Heat connections.
2. Poor circuit between the relay and 2. Check the bus bar connector and wirbus bar. ing.
3. Poor contact between bus bar and plugs. 3. Check that the bus bar is free of corrosion and glow plug nuts are tight.

Glow Plug Relay 1. Timer is not working properly. 1. Check the timer Refer to "Component
Turns On, But Does Inspection." Check the timer ground.
Not Turn Off 2. Poor circuit between the relay and 2. Check the wiring and connections.
the timer.
3. Worn relay. 3. Check the relay for continuity Refer to "Component Inspection."

Indicator Lamp Does 1. Bulb is burned out. 1. Check the bulb.
Not Light 2. Worn timer 2. Check the timer Refer to "Component
Inspection."

DIAGNOSIS OF PREHEAT PROBLEMSENGINE COOLANT TEMPERATURE ABOVE 0~C (32~F)

PROBLEM POSSIBLE CAUSE CORRECTION

Indicator Lamp Does 1. Bulb is burned out. 1. Check the bulb.
Not Light 2. Worn timer. 2. Check the timer Refer to "Component
Inspection."

Glow Plug Relay 1. Thermal switch disconnected. (indi- 1. Check the connection.
Turns On cator lamp will light for 3.5 seconds.)
2. Thermal switch stuck open. (Indi- 2. Check the switch. Refer to "Compocator lamp will light for 3.5 seconds.) nent Inspection."
3. Poor timer ground. 3. Check the ground connection.
4. Poor circuit between timer terminal 4. Check the wiring and connections. 5 and relay.
5. Worn timer. 5. Check the timer Refer to "Component Inspection."