Fault Monitoring - Webasto Air Top 2000 STC Workshop Manual

3 Function description

3.8.1 Fault monitoring

Overheating, incorrect start and flame failure faults are
counted and, after the maximum number of permissible
faults have been exceeded, result in heater lock-out.
The incorrect start counter is incremented by 1 each time the
heater fails to start and decremented by 1 each time it starts
correctly, but never falls below 0. If the incorrect start coun-
ter reaches the maximum permissible value of 7, this indi-
cates that the heater is in heater lock-out mode (HGVP).
The fault counter is incremented by 1 for each malfunction,
which does not have its own counter. The fault counter is
reset to 0 at the start of control mode. If the fault counter
reaches the maximum permissible value of 10, this indicates
that the heater is in heater lock-out mode.
The overheating counter is incremented by 1 each time the
heater overheats. If the overheating counter reaches the
maximum permissible value of 20, this indicates that the
heater is in heater lock-out mode.
The flame interruption counter (FAZ) is incremented by 1
each time the flame fails during heating mode. The counter
is decremented by 1 each time the heater assumes control
mode.
If the flame interruption counter reaches a value of 3 the
heater will assume fault lock-out mode and the permanent
flame interruption counter is incremented by 1. In control
mode, the permanent flame interruption counter is decre-
mented by 1. When the heater is burning properly again, the
permanent flame interruption counter will return to 0 after a
few control cycles. If the permanent flame interruption coun-
ter exceeds the maximum permissible value of 3, the heater
will assume heater lock-out mode.
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3.8.2 Resetting fault switch-off
1. Switch on the heater
2. There is a fault and it is detected by the control unit
as a malfunction
3. The fault code is shown on the control element
4. If set, cancel heater lock-out (as described in the fol-
lowing)
4.1. The heater detects a fault as a malfunction
4.2. Fault switch-off followed by fault lock-out
4.3. The fault code is shown on the control element
5. Switch off the heater
6. Determine cause of fault (e.g. with or without fault
code, visual inspection of fuses and plug connections,
...)
7. Rectify fault
8. Switch on the heater
9. Reset fault lock-out
10. The heater assumes control mode
Certain faults add to the fault count in the fault code mem-
ory. The heater assumes heater lock-out mode when the
number of faults in the fault code memory exceeds a limit
value. The maximum number of fault in the fault code mem-
ory and the limit value of the fault code memory is defined by
Webasto.
Reset heater lock-out
Heater lock-out can be reset:
– With Webasto Thermo Test PC diagnostics (WTT)
– or by switching on the heater.
Pull fuse F1 for at least 10 s.
Switch off the heater.
Reinsert fuse F1.
Switch on the heater.
Reset permanent heater lock-out
Only for "OE" heater variants that are integrated in bus sys-
tems.
The lock-out can only be released with the vehicle-specific
computer diagnosis system.
Air Top 2000 STC