Failure Symptoms After Switch-Off Upon Failure - Webasto Thermo 90 Workshop Manual

5 T
ROUBLESHOOTING
5.3 Failure Symptoms after Switch-off
upon Failure
When operated with a switch the type of failure is
indicated by a flash code of the operation indicator light
during heater run-down.
After five short signals the long flash pulses are counted.
Failure Symptom
No function
1 Flash pulse (F 01)
(no start)
2 Flash pulses (F 02)
(flame-out during operation)
3 Flash pulses (F 03)
(low voltage)
4 Flashes (F 04)
(flame sensor
continuously hot)
5 Flash pulses (F 05)
(flame sensor)
6 Flash pulses (F 06)
(temperature sensor)
7 Flash pulses (F 07)
(fuel metering pump)
(temperature limiter)
Fig. 5-2
5-2
NOTE:
Probable Cause
Electrical wiring, fuses
Control unit defective
Fuel system
Combustion air/exhaust duct
Burner
Fuel supply
Burner
Electrical power supply
Flame sensor defective
Wiring
Flame sensor defective
Wiring
Temperature sensor defective
Wiring
Fuel metering pump defective
Coolant circuit (Thermo 90 only)
Failure Symptoms after Switch-off upon Failure (Part 1 of 2)
The heater Thermo 90 S, with standard timer, outputs
errors to the timer display for indication (see 3.6.3).
The following table may also be used as representative
reference.
Remedy
Check fuses
Check battery connections
+ at A5 / – at A3 / + from A1
(Thermo 90)
+ at 12 / – at 9 / + at 3, connector X12
(Thermo 90 S)
Replace control unit
Check fuel level
Check fuel filter
Bleed fuel system
Check combustion air/exhaust duct for
foreign matter and clean as required
Clean burner or replace as necessary
Check fuel level
Check fuel filter
Bleed fuel system
Clean burner or replace as necessary
Check battery (load test)
Check electrical connections
Replace flame sensor
Check wiring for damage, open
connections or short circuit
Replace flame sensor
Check wiring for damage, open
connections or short circuit
Replace temperature sensor
Check wiring for damage, open
connections or short circuit
Replace fuel metering pump
Check coolant level
Bleed coolant circuit
Reset temperature limiter
T 90 / 90 S
HERMO