507
Thermo plus 160/230/300/350 5 Troubleshooting
5.5.3 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 sys-
tem, the temperature of optional components, such as the
nozzle block preheater, circulating pumps or heatable
filters.
NO
YES
Is the battery charge condition permanently
greater than 20.5V ± 0.5V?
Ensure permanent battery voltage greater
than 20.5V ± 0.5V.
Disconnect the C plug from the control device.
Is the voltage between pin 2 and 1 as well as pin
4 and 3 of plug C at least 20.5V ± 0.5V?
Is the electrical connection to the heater OK?
(fuse, wiring harnesses, plug connections,
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 ± 0.5V? (Verify with STT diagnosis.)
Ensure higher voltage during heater
start and/or heating operation.
Control device defective, replace it.
To Next Page
