Viessmann Vitocal 350-A Installation And Service Instructions Manual page 144

Troubleshooting
Control unit diagnostics
Message
System characteristics Cause
«B4 AD converter
«B5 EEPROM
«B9 KM BUS solar
«BA KM BUS Mi/HC
«BC HC1 R/C KM BUS
«BD HC2 R/C KM BUS
144
(cont.)
Internal fault ADC (ana-
logue digital converter,
reference), ribbon cable
between sensor PCB
and main PCB faulty, or
PCBs faulty
Internal fault, EEPROM
Communication error -
KM BUS solar control
unit, or sensor S3 of
Vitosolic faulty
KM BUS communication
error or internal fault in
extension kit for one
heating circuit with mixer
M3
Communication error -
KM BUS remote control;
heating circuit without
mixer A1
Communication error -
KM BUS remote control;
heating circuit with mixer
M2
Measures
Check sensor connec-
tions F1, F5, F10, F15,
F19 and F22 on PCB 3.
Never connect any exter-
nal components. Check
PCB; if required, replace
in the following order:
PCB 3, PCB 2, program-
ming unit.
Replace coding card.
■ Check parameter
"Vitosolic type".
■ Check connection to
Vitosolic.
■ Check sensor S3 and
replace if required.
Installation and
service instruc-
tions, Vitosolic
Check extension kit con-
nections and code.
Check remote control
connections and code;
switch ON remote con-
trol.
Check remote control
connections and code;
switch ON remote con-
trol.