This instruction show you guide on how to solve AGCO tractor DTB DT205B trouble code D121.
The alternator voltage regulator voltage is too high (filtered battery signal) (X55).
Related Contents:
AGCO EDT Electronic Diagnostic Tool
Possible causes
The filtered battery supply voltage is above 15.5 V
The alternator voltage regulator is faulty
The instrument panel voltage filter system is faulty
Consequences
There is a risk of overvoltage causing damage to the tractor electrical components.
D121 error code: diagnostic file
Check fuses F38 and F12.
Checking the voltage supplied by the two alternators
Test the voltage between terminal 1 of connector X192 or terminal 1 of connector X193 and the earth.
Note:
For more information about the alternator test, refer to the workshop manual.
Erase any errors in the instrument panel and check that the error code does not re-appear.
Change the alternator voltage regulator. Repair the electrical fault if necessary.
Replace the instrument panel. The condenser inside the instrument panel may be faulty.
Note:
Before replacing the instrument panel, check to make sure that the two voltage input terminals for the instrument panel are correct. Terminal 1 of connector X55 is connected to a + supply when the ignition is switched on. Terminal 68 of connector X55 is connected to a permanent + supply.
Carry out a test, while checking to ensure that the error code does not re-appear.
