Checking Exhaust Gas Temperature Sensor; Checking Control Unit; Check Combustion Tube - Webasto Thermo Top Pro 120 Workshop Manual

7.3 Checking exhaust gas temperature
sensor
When testing with a digital multimeter, the exhaust gas temper-
ature sensor should show the following values:
Resistance at 20 °C: 2130 - 2230 ohms.
Connectors and con- no
tacts OK?
yes
Cables damaged or
yes
ceramic element
broken?
no
Resistance measure- yes
ment with digital mul-
timeter, is resistance
outside the
2130-2230 Ohm
range?
No
Component is OK.
NOTE
Check the exhaust gas temperature cable for signs of
mechanical damage from the outside.
NOTE
If the exhaust gas temperature sensor suffers external
mechanical damage, this component can be replaced
without the need for additional work.
9039412C Workshop manual TTP 120 _ 150
Replace
com-
ponent.
Replace component.
Replace component.
7.4

Checking control unit

PC and Webasto For the fault code:
Thermo Test dia-
yes See chapter 6.6, "Overview of faults
gnosis adapter:
and fault codes" on page 17.
Fault codes have
For changing components:
been read out,
See chapter 8.6, "Removing control
fault code present?
unit" on page 30.
no
Connectors and
no
contacts OK?
Replace
yes
compon-
ent.
Externally dam-
aged?
yes Replace
Optical sensor de-
compon-
fective?
ent.
No
Component is OK
NOTE
– The control unit has an optical sensor (flame monitor).
– Clean the sensor before installing the control unit, if
necessary.
– Replace the whole control if it is defective.
7.5

Check combustion tube

Combustion tube Replace compon-
mechanically dam-
yes ent.
aged?
no
Combustion tube
yes
fouled?
Rectify cause. Replace component if
no
necessary.
Component is
OK.
Function checks | 7
A
A = Optical sensor
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