DISCLAIMER: YOU DO THIS AT YOUR OWN RISK AND MAY VOID THE MANUFACTURERS WARRANTY.

DIAG mode allows user to check tons of stuffs inside the electronic brain of the XT. It also allows Yamaha servicing to check previous problems too.

To access DIAG mode :

switch off Engine Run switch, switch OFF Key switch. Press both SELECT & RESET buttons and then switch ON Key switch. Keep SELECT & RESET buttons pressed for at least 8 seconds. Display then changes to "DIAG". Release SELECT & RESET buttons.
Select Diag mode by pressing again both SELECT & RESET buttons.
Select code below by pressing SELECT (up) or RESET (down).

Diag Code Number

Part I : Sensors

01 : Throttle position - must be from 15-17 (closed) to 97-100 (opened)
02 : Atmospheric pressure given in mmHg (normal is 760 - average weather)
03 : Differential pressure between air and intake pipe
05 : Air intake temperature (in Celcius)
06 : Cooling liquid temperature (in Celcius)
07 : Absolute speed (must be 000 in garage). Check with rear weel.
08 : Lean angle safety switch control - must be from 0.4-1.4 (upright) to 3.8-4.2 (horizontal). DISMOUT THE SWITCH FOR CHECKING !!!
09 : Battery voltage - must be above 12.0
20 : Side stand switch - displays ON or OFF
21 : Neutral gear switch - displays ON or OFF

Part II : ECU memory check.

60 : EEPROM error code presence - 00 means no default, 01 or 02 means default on corresponding cylinder (blinks if both cylinders).
61 : Error Code memory log - Displays 00 if no error code in memory, displays the Error Code if any (11 to 50). Display changes every two seconds if more than one Error Code in memory, then start again from first.
62 : Displays the number of Error Code in memory. To clear the memory, switch the Engine Run Switch to ON position (no backup).
70 : Check Code number, display from 0 to 255

Part III : Activators - To activate, turn Engine Run switch from OFF to ON - Engine check light is activated too.

30 : Coil 1 is activated 5 times per second.
31 : Coil 2 is activated 5 times per second.
36 : Injector 1 solenoid is activated 5 times per second.
37 : Injector 2 solenoid is activated 5 times per second.
48 : Air duct solenoid is activated 5 times per second.
49 : Air intake solenoid is activated 5 times per second.
50 : Fuel injection relay is activated 5 times per second.
51 : Cooler fan is activated every 5 seconds.
52 : Headlight relay is activated every 5 seconds (2 seconds ON, 3 seconds OFF) - 2003+ model only.

DISCLAIMER: YOU DO THIS AT YOUR OWN RISK AND MAY VOID THE MANUFACTURERS WARRANTY.