44
8.10
Faulty engine-speed measuring channel
In the case of an error message concerning engine-speed measurement:
- Check that the selector button for 2-stroke / 4-stroke is correctly set.
- Check whether the fault can be remedied by installing a new clamp-on speed sensor.
- Check the pulse input.
This check can be made without opening the device.
The engine-speed input can analyze square-wave signals from U
SS
> 2 V if they are sufficiently steep. The interpulse period is without
significance, provided that the interval between the shorter edges is no less than 5 ms.
Connect the square-wave generator (5 Hz to approx. 150 Hz) to the engine-speed input as illustrated.
The signal polarity is unimportant.
Set signal amplitude to U ZV.
Set signal frequency to 5 Hz.
Start analysis on the exhaust-gas analyzer
Frequency
Displayed value
(press "Pump" button). Test the signal frequencies
(Hz)
2-stroke
4-stroke
in accordance with the adjacent table.
If the result of this test is negative, the exhaust-gas
5 Hz
1200 rpm
600 rpm
analyzer must be opened.
to
to
to
39.5 Hz
9480 rpm
4740 rpm
40 Hz
- - - -
4800 rpm
to
- - - -
to
79 Hz
- - - -
9480 rpm
80 Hz
- - - -
- - - -
- On the "sensor board" module, check that the supply voltages are being fed correctly.
- Check power supply to sensor board according to Section 8.15.
If faulty, additionally check power supply to motherboard to Section 7.17. Replace defective components as appropriate.
- If the voltage supply is intact, in order to isolate the problem, check whether the input pulses on the sensor board are being processed.
To do this, connect the logic probe of the oscilloscope to the test point (INT-O) of the sensor board
(reference point MA-X83, PSVD = X 82).
- Repeat the above test of the pulse input using a clock-pulse generator.
L-pulses can be measured with a logic probe.
If measuring with an oscilloscope:
Each edge change of the input signal generates an L-pulse of 5 ms
The signal can also be measured on the motherboard at test plug X 30 b 19.
!
Extra caution is necessary for this type of measurement. Do not cause a short circuit between the pins!
Depending on the results of your tests, replace the sensor board, motherboard or connecting cable.
G
1
2
3
459512/5Ha
2 V
Summary of Contents for ETT 008.31
Page 1: ...1 Repair instructions Exhaust gas analyzer ETT 008 31 ETT 008 38 ...
Page 48: ...48 8 15 5 Sensor board component location diagram ...
Page 51: ...51 8 17 1 Motherboard component location diagram ...
Page 61: ...61 12 Diagrams circuit diagrams and gas route diagram 12 1 Circuit diagram 1 ...
Page 62: ...62 12 2 Circuit diagram 2 ...
Page 63: ...63 12 3 Gas route diagram ...
Page 65: ...65 ...
