Checking For An Obstruction; Checking The Pressure Switches - Bosch ETT 008.31 Repair Instructions

8.2.1 Checking for an obstruction

In the zero-gas system:
- Open the device.
- Remove coarse filter GF 4 from hose 8.
- Press the "Pump" button.
Error message remains:
Error message remains:
Error message no longer shown: Solenoid valve is not switching over.
In this case, measure the control voltage at the solenoid valve or at connector X 5 pins 1 and 2 on the "power electronics" module:
VDC = 24V.
The solenoid valve is triggered upon each zero adjustment (approx. 30 seconds) and each time the pump is switched off following
analysis for the purpose of purging the device (approx. 15 seconds).
Control voltage OK:
Control voltage faulty:
Replace faulty components as appropriate.
In the test-gas system:
- Remove hose from the test-gas inlet.
- Press the "Pump" button.
Error message remains:
Error message remains:
Error message remains:
Error message remains:
If you are unable to detect an obstruction, perform the checks described in Sections 8.2.2 to 8.2.4.

8.2.2 Checking the pressure switches

Diagram, pressure switches with circuitry
Remove hose 9 from test-gas pump, press "Pump" button.
Perform check to Sections 8.2.2 to 8.2.4, or
Replace solenoid valve.
Check power supply to power electronics to Section 8.16.
Remove condensation tank, press "Pump" button.
Remove condensation tank, press "Pump" button.
Open exhaust-gas analyzer and remove hose 9 from the test-gas pump, press "Pump" button.
Remove hose 7 from gas and condensate pump, press "Pump" button.
Power electronics
Motherboard
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