Bosch TCA640 Series Repair Instruction page 88

7.5.5 Heater is not functioning
Fault description:
Is not heating, error message ERROR 1, ERROR 5
Possible faults:
1. No control signal voltage from logic module
2. No voltage at power module heater output
3. No voltage at thermal release input
4. No voltage at heater connection
Troubleshooting:
1. Check control signal voltage from logic module
To do this, open the appliance. Using the Torx T10 screwdriver,
unscrew all rear panel screws and remove the rear panel. Remove
upper appliance cover to the rear. Remove both side panels upwards.
The control signal voltage is measured on plug CL10 on terminals 1 =
GND and 4 = 5 VDC. The heater must be actuated by drawing hot
water. The heater is actuated in pulses.
→
►
No control voltage
defective
→
►
Voltage available
2. Check voltage on power module heater output
The voltage for the heater is measured on plug CP6 on terminal 5 =
neutral conductor (blue) and terminal 1 = phase (brown). From service
index 02 on the heater is connected between terminals TM3 and TM5.
The heater must be actuated by drawing hot water. The heater is
actuated in pulses.
→
►
No voltage defective power module
→
►
Voltage available
58300000120060_ARA_en_c.doc – 18.09.09
Logic module or connecting cable
see Point 2
see Point 3
3. Check voltage on thermal fuse input
The operating voltage of the heater (= 230 VAC) is measured at the
thermal fuse input (brown = under the insulation sleeve) and on the
blue terminal on the heating element.
→
►
No voltage defective wiring
→
►
Voltage available
4. Check voltage on heater connection
The operating voltage of the heater (= 230 VAC) is checked on the
terminals of the heating element (brown = neutral conductor; blue =
phase).
→
►
No voltage Thermal release defective
→
►
Voltage available
see Point 4
defective heating element
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