Webasto Thermo Pro 90 Workshop Manual - 5 Faults, Troubleshooting
5 Faults, Troubleshooting
Thermo Pro 90
501
5
Faults, Troubleshooting
General
This section describes troubleshooting on the Thermo Pro 90
heater.
IMPORTANT
Troubleshooting work demands precise knowledge of the
structure and theory of operation of the various compo-
nents and must be carried out by trained personnel only.
In case of questions, the functional relationships are
IMPORTANT
Error detection is generally limited to the localisation of the
defective components. The following fault causes are not
taken into account and should always be checked or a fault
should be excluded for the following reasons:
• Corrosion on connector
• Loose contact on connector
• Crimping error on connector
• Corrosion on lines and fuses
• Corrosion on battery terminals
• Impermissible high ambient temperature
Each time an error is eliminated, a functional check must be
carried out in the vehicle; switch the heater off and on again
beforehand.
Procedure in case of errors or faults and lock-outs
IMPORTANT
Always determine the error cause for the lock-out first, then
eliminate the lock-out.
If errors occur in the heater, they will be detected by the
control unit as a fault. Depending on the type and weight-
ing of the fault, a fault run-on can be initiated. When a fault
run-on is initiated, the heater remains in the fault lock-out.
In addition, a error code is output after a fault is detected
during the fault switch-off.
The error code is displayed via:
–
the operation indicator or
–
the "ON/OFF" switch or
–
Reading out of the error memory with Webasto Thermo
Test PC Diagnosis.
The error code is used by the workshop or the authorised
Webasto dealer for troubleshooting.
NOTE
In the Webasto Thermo Test PC Diagnosis, W bus must be
selected under “Diagnosis” => “Device selection”. It is rec-
ommended that the operating and fault data and the
extended fault environment conditions be printed out.
Fault causes
A fault occurs when one or more error have occurred. Pos-
sible errors are, e.g.
– Overvoltage/undervoltage
– Malfunctions of all components, e.g. due to a short cir-
cuit or open circuit
– Overheating of the heater
– Impermissible exhaust temperature
– False starts
– Flame failures
Elimination of faults without Webasto Thermo Test PC
Diagnosis
Switch on heater
(switch/standard timer)
An error has occurred and is detected by the control unit
as a relevant
fault
Heater switches off due to the error, i.e. fault switch-off
with subsequent
fault lock-out
.
The error code is output with the switch/standard timer.
Determine error cause (e.g. with or without
error code
output
, visual inspection of fuses and connectors, etc.)
Eliminate error
Switch off heater
Switch on heater
Fault lock-out
unlocked
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