MTZ 952 - Page 51

Controls and Instrumentation
MTZ series 900
20
Table 12
Contact
Address of the XP2 connector pin
1
To the terminal “–“ (common)
2
To the control board contact “Indication Mode”
3
To the control board contact “Parameter Selection”
4
To the control board contact “Parameter Value”
5
6
7
To the fuel volume sensor
8
To the control board contact “M”
9
To the control board contact “+UBZ”
1.12. Indicator Diagnostics and Troubleshooting
1. No instrument backlight:
Check the power supply voltage at the pin “9” of the 13-contact of the contact block (ХР1)
of the instrument (Fig. 5);
2. Jerking and jumps of the pointer of the engine rotational speed indicator over
the dial: poor contact on the alternator terminal and, therefore, poor signal from the
phase winding of the alternator. Repair.
3. Jerking of the pointer and understating the reading of the engine rotational
speed:
- Check and adjust the tension of the alternator driving belt.
4. Over- or understated readings of the engine and PTO’s rotational speeds (with
the normal movement of the pointer):
- Check the correctness of programming the instrument according to the gear ratio of the
alternator drive (parameter “K”): (see item 1.10);
5. The counter of astronomical hours of the engine running fails to accumulate the
operating time:
- Check the connection of the wire to the contact «8» of the instrument block (ХР1) and
the presence of the frequency signal from the phase winding of the alternator.
6. Over- or understated readings of the tractor speed:
1. Check the correctness of the instrument programming according to the rolling radius of
the rear wheels (R) (see item 1.10);
2. Check the correctness of the programming according to the number of teeth of the
half-axle pinion (Z) (see item 1.10).
3. Check the correctness of programming the multiplying factor of the gear rate of the
wheel reduction gear (I) (see item 1.10).
7. The “FUEL” reading appears on the indicator display
Check the connection and serviceability of the frequency fuel volume sensor (FFVS) to
the contact “7” of the block (ХР2).