The golw plugs are used to heat the inlet air and able to start the engine.
This heating is necessary to allow the diesel fuel to ignite when the temperature low.
The ECM controls the feed to preheating resistor via one relay.
When the ignition switch is turned on, applies the battery voltage from the heater fuse to the ECM.
The glow plug relay coil is energized to turn on the relay switch, which activates the glow plugs by the ECM, according to the signal of water temperature sensor. Feed faults are diagnosed by the ECM via the lines connected to the control terminal of the heater relay. The duration of preheating and illumination of glow indicator lamp are entirely controlled by the injection computer depending on the engine operating conditions.
In case of the glow plug relay failure, the engine symptoms will occur the glow plugs deactivation and the engine starting delayed during the cold condition.
If the signal exceeds threshold value, the ECM judged this as a fault and DTC is set.
Item
Detecting Condition
Possible Cause
DTC Strategy
? Circuit continuity check
? Short to battery in power circuit
? Short to battery in control circuit
? Faulty relay
? Faulty ECM
Enable Conditions
? Ignition on
Threshold Value
? Short for glow relay control circuit
Diagnostic Time
? 1 sec.
MIL
Fuel Limit
Fuel Cut
EGR Off
? No
Fail safe
? Engine speed is fixed as 1200 rpm without the accel position sensor action.