Sprinter 3500 L5-2.7L DSL Turbo (2004)
Glow Plug: Description and Operation
Pre-Glowing
With the key in the On position, the glow plug output stage and the indicator lamp are actuated by the ECM. The pre-heating time is calculated by the
ECM in line with the coolant temperature. The glow plug output stage switches the current through the glow plugs. The glow plug indicator lamp goes
out after a pre-glow period has elapsed. Component or cable failures in the pre-glow system are indicated by the glow plug lamp and stored in the ECM.
Glow Output Stage
With the ignition key in the On position a signal is transmitted from the ECM to the glow plug output stager. If no data is exchanged with the ECM the
glow plug stage is terminated after two seconds. The glow plug out put stage constantly signals the current operating state (ON/OFF) and any system
faults. The following faults are recognized by the out put stage and transmitted to the ECM:
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Open circuit in one or more of the glow plug leads
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Short circuit in the glow plug circuit
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Out put stage fault or temperature related shut-off.
If a failure in the glow plug system occurs, the glow plug indicator lamp will be illuminated only as long as the fault is current. If the failure is no longer
present, the glow plug indicator lamp will be switched off but a code will be stored in the ECM.
After Glow
Once the engine has started, the ECM determines the after glow time depending on cooling temperature. During this time the glow plugs continue to be
actuated by the glow plug output stage. This results in improved smooth running after a cold start and improved warming up properties, elimination of
blue exhaust after a cold start up and a more stable cold starting speed.
If no signal is received from the coolant temperature sensor the signal from the oil sensor is used as a substitute.
