83-410 Function test
Commercially available tool
Thermometer -20°C to +70°C
Note
Perform function test at approx. 20°C (room
temperature) and with engine cold.
Preparations for function test
1 Attach exhaust extractor to tailpipe of
exhaust silencer.
2 On model 124.0 up to approx. 09/92
(excluding models 124.034/036) detach 2-pin
plug connection X73 in engine compartment,
except for model 124.020 with automatic
heater control. On model 124.020 with
automatic heater control, detach relay K15
(2-pin connector X73 is not fitted)
3 On models 124.1/2/3 detach 2-pin plug
connection X73 in engine compartment,
(excluding models
Arrangement
124.120/128/133/188/193/3 as of approx.
02/93 and models 124.126/129/131/186/191) X73 Plug connection - circulation pump relay
(excluding model 124.020 with automatic
(2-pin connector X73 is not fitted).
heater control and models
124.019/022/028/032/034/036/042/052/
066/079/082/088/092)
Arrangement model 124.036
X73 Connector - circulating pump relay
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Note
The relays with connectors may be arranged
as desired in the relay holder. If relay K15 is
disconnected, the circulation pump no longer
operates with the ignition switched on and
the temperature selectors set to "MAX".
4 Switch on ignition. There must not be any
coolant temperature reading on the
instrument cluster.
5 Switch off ignition.
6 Close left and right side vents and also
center vents.
7 On vehicles without automatic climate
control:
turn airflow switches to the arrow pointing
upwards.
Turn left and right heater switches or
temperature selectors to "MAX".
Heater
switches on model 201
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8 On models with automatic climate control:
press pushbutton (arrow) "DEF" and turn
temperature selector (arrow) to "MAX".
9 Insert thermometer into left-hand
defroster vent.
Function test
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Switch on auxiliary heater with the instant
heat button.
Green operating indicator lamp of timer
comes on.
Yes No
1 Fuse (8A) faulty
(see wiring diagrams in Electric
Wiring Diagrams file).
2 Test timer (83-415).
Glow plug pre-glows, air around glow plug is
heated.
Yes No
Test glow operation (83-440).
Note
On models as of approx. 08/86 with
control unit 105.499 (Webasto
number) the combustion air blower
starts up immediately for approx. 60 s
if the glow operation is faulty before
the heater switches to fault.
After approx. 35 s the combustion air blower
can be heard to start.
Yes No
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Check whether green operating
indicator lamp of timer is off.
Yes No
Replace flame monitor
(83-436).
Test combustion air blower (83-455).
Combustion commences, exhaust pipe
becomes hot.
Yes No
Wait for repeat start, repeat start
follows.
Yes No
1 Check state of charge of
battery.
2 Check glow operation
(83-440).
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Combustion commences, heater
running.
Yes No
1 Check temperature cut
out (83-450).
2 Check fuel metering
pump (83-480).
3 Check flame monitor
(83-435).
4 Check state of charge of
battery.
The heater blower starts up automatically
approx. 6 min after commencement of
combustion.
Yes No
See troubleshooting information
(83-409).
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The air outlet temperature must be at 45°C
approx. 2. min after the heater blower
switches on.
Yes No
Refer to troubleshooting information
(83-409).
Switch off auxiliary heater by pressing the
instant heat button.
End of test
After completing the repairs on model 124,
reinstall 2-pole connector X73 or relay K15.
Note
The controlled mode has not been tested.
Refer to troubleshooting information (83-409)
for complaints.
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