Operating instructions

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015 Too many overheats The control unit is interlocked after three successive

overheats (error codes 012, 013 and 014). Eliminate the

case of the overheat. Cancel the interlock by clearing the

error memory with the diagnostic unit/PC.

020 Open circuit - glow pin Check glow pin (nominal value: 2 ohms), replace if

necessary. Check pin 4(white) on the control unit

021 Short circuit - glow plug (internal plug) leading to glow plug to terminal 3 (brown)

for continuity/short-circuit. If O.K.-> replace control unit.

033 Combustion air blower motor Speed deviation for longer than 60 seconds. Nominal

values: 5600 rpm (full-load), 1850 rpm (part load)

* Check burner motor: apply supply voltage to motor.

Connect + to 1.5 black and - to 1.5 orange. Motor does

not turn —> replace burner motor with integrated sensor.

* Check sensor supply. Switch on heater and measure

voltage between output 13 (0.25 red) and 14 (0.25 green)

at the control unit (internal plug). Nominal value: 8 V. If

deviation —> replace control unit.

* Check sensor: Measure voltage between terminal 15

(0.25 violet) and 14 (0.25 green) with an analog voltmeter

when the blower is running. Nominal value: 4 V (+ 0.3 V)

average value (8 V square-wave signal). If deviation —>

replace motor with integrated sensor. If sensor signal is

O.K., then the speed controller is defective —> Change

control unit.

037 Water pump is not working Check water pump (driven externally).

042 Water pump short-circuit Check water pump and leads.

043 Short circuit at external components Check terminal 2 (1 green) of control unit (external plug)

for short-circuit. Check connected components (max.

current 6A), replace them if necessary.

047 Short circuit - fuel metering pump Check terminal 1 (1 blue) of control unit (external plug)

and leads up to metering pump for short-circuit/

interruption. Check the metering pump. Nominal value:

048 Open circuit - fuel metering pump approx. 20 ohms. Replace if necessary.

88 sseeccoonnddss