Bosch TCA640 Series Repair Instruction page 87

7.5.4 Pump is not functioning
Fault description:
Pump is not actuated / is not pumping
Possible faults:
1. No control signal voltage from logic module
2. No voltage at power module pump output
3. No voltage at thermostat input
4. No voltage on the pump
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 (brown) and 8 = 5 VDC (grey). The pump must be actuated by a
coffee brewing process.
→
►
No signal voltage
fective
►
Voltage available ? see Point 2
2. Check voltage on power module pump output
The voltage for the pump is measured on plug CP6 on terminal 1 =
phase and the neutral conductor, terminal 4. The pump must be
actuated by a coffee brewing process.
→
►
No voltage defective power module
→
►
Voltage available
58300000120060_ARA_en_c.doc – 18.09.09
Logic module or connecting cable de-
see Point 3
3. Check voltage on thermostat input
Before the voltage can be checked on the pump itself, the thermostat
must be tested for function. The pump must not be overheated!
The voltage is measured at the thermostat input – on the right (grey
cable from power module) and at the thermostat output – on the left
(grey cable at pump connection. In both cases the phase connection
(black) of the pump is used as the anti-pole. The pump must be
actuated by a coffee brewing process.
►
No voltage at the thermostat input
►
No voltage at the thermostat output
►
Voltage available at thermostat output
4. Check voltage on the pump
The pump operating voltage is checked at the terminals of the pump.
→
►
No voltage defective thermostat
→
►
Voltage available
→
defective wiring
→
defective thermostat
→
see Point 4
defective pump
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