Viessmann VITOCAL 300-G Installation And Service Instructions Manual page 141

Messages
(cont.)
Message
System characteristics Cause
BA KM BUS mixer HC
BB KM BUS mixer cooling
BC KM BUS R/C HC1
BD KM BUS R/C HC2
BE KM BUS R/C HC3
BF Communication module
KM BUS communication
error or internal fault in
extension kit for one
heating circuit with mixer
M3
KM BUS communication
error or internal fault in
extension kit, NC-Box for
cooling circuit
Communication error -
KM BUS remote control;
heating circuit without
mixer A1
Communication error -
KM BUS remote control;
heating circuit with mixer
M2
Communication error -
KM BUS remote control;
heating circuit with mixer
M3
LON communication
error; incorrect LON
communication module
Troubleshooting
Measures
Check extension kit con-
nections and code.
Check connections and
parameter settings.
Check remote control
connections and code;
switch ON remote con-
trol.
Check remote control
connections and code;
switch ON remote con-
trol.
Check remote control
connections and code;
switch ON remote con-
trol.
Check connections and
type of communication
module LON. Replace in
the following order if
required:
■ Control and sensor
PCB
■ Ribbon cables between
controller and sensor
PCB and main PCB
■ Main PCB
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