Truma Combi Service Handbook

The Blue Pages: 12VDC
Component Measuring points Function/Setpoint Remark
Ignitor (step 1)
Pull out X7 plug
Apply 12 V between X7-11 (+) and
X7-10 or 9 (-)
Ignition spark can be
heard and seen
If you cannot hear the ignitor ticking,
replace the ignitor
Combustion air motor
Pull out X7 plug
Apply 12 V between X7-2 (+) and
X7-5 (-)
Motor runs at full
speed
If you cannot hear the motor running,
replace the motor
Air Circulation D.C. motor
Pull out X3 plug
Apply 12 V between X3-1 (+) and
X3-2 (-)
Motor runs at full
speed
If you cannot hear the motor running,
replace the motor
Solenoid coil “small”
Pull-in winding
Pull out X7 plug
Apply 12 V (< 5 sec.) between
X7-18 (+) and X7-20 (-)
You hear the solenoid
valve opening
If you cannot hear the solenoid valve
opening, replace the coil
Solenoid coil “large”
Pull-in winding
Pull out X7 plug
Apply 12 V (< 5 sec.) between
X7-15 (+) and X7-17 (-)
You hear the solenoid
valve opening
If you cannot hear the solenoid valve
opening, replace the coil
Component Measuring points Function/Setpoint Remark
Ignitor (step 2) Switch on the furnace
Voltage measurement between
X7-10 or 9 and X7-11
Minimum voltage
10 V
If no voltage is measured when the
solenoid valve has opened or if it
is less than 10 V:
- detach the plus or minus cable
from the ignitor (ignitor short
circuit input side) or
- replace the electronics
Air Circulation D.C. motor Switch on the furnace (ΔT > 2° C),
voltage measurement between
X3-1 and X3-2
4.5-12 V
(speed is controlled
by LTF)
If the voltage is less than 4.5 V,
replace the electronics
Solenoid coil “small”
Hold-in winding
Switch on the furnace (ΔT ≤ 2° C)
voltage measurement between
X7-18 and X7-19
Minimum voltage
10 V
After start ramp, consistent voltage
If not, replace the electronics
Solenoid coil “large”
Hold-in winding
Switch on the furnace (ΔT > 2° C)
voltage measurement between
X7-15 and X7-16
Minimum voltage
10 V
After start ramp, consistent voltage
If not, replace the electronics
CP Plus digital control panel Voltage measurement on contact pin,
12 VDC supply cable
Minimum voltage 8
VDC
If voltage present, replace control
panel. If no voltage measured,
replace electronics
Voltage: Applied
Voltage: Measured

Truma Combi Specifications

General

Type	Combination heater
Fuel	LPG
Water capacity	10 liters
Control	Digital control panel
Safety Features	Overheat protection, flame monitoring
Efficiency	Up to 90%