507
Thermo G
5 Troubleshooting
5.4.3 Error symptom "Low voltage"
A value is stored in the control unit as smallest "permis-
sible low voltage".
It must be noted that the voltage may be lowered during
heater start, and that the "low voltage" threshold may be
violated.
Among others this depends on the vehicle electrical
system, the temperature of optional components, such as
the circulating pumps or the electrical regulator heating.
NO
JES
Is the battery charge condition permanently
greater than 20.5V (measured at heater)?
Ensure permanent battery voltage greater
than 20.5V.
Disconnect the C plug from the control unit.
Is the voltage between pin 1 and pin 2 of plug
C at least 20.5V?
Is the electrical connection to the heater
OK? (fuse, wiring harnesses, plug connec-
tions, pins, etc.)
Repair or replace the
electrical connection to
the heater.
Start heater: Is the voltage permanently applied to the heater during heater start
or during heating operation 20.5V?
Ensure higher voltage during heater
start and/or heating operation.
Control unit defective, replace it.
