Diagnostic Light Check (All Models Except Z915B)
The electronic control unit provides a diagnostic light to help
the operator identify operational and electrical problems by flashing
a diagnostic code.
Diagnostic “Real Time” Codes
Park machine safely. (See Park Safely in SAFETY section.)
NOTE: The operator can be seated on the machine or standing
next to the machine.
Turn the key to the START position and release key to RUN mode.
A - Engine Diagnostic Indicator Light (A) is used for
Z925M EFI and Z930M EFI engines only. Light will be on if active engine
diagnostic code is present. See your John Deere dealer.
B - Vehicle Diagnostic Indicator Light (B) will flash
a diagnostic code to help the operator identify operational and electrical
C - PTO Indicator Light (C) will flash a diagnostic
code to help the operator identify if PTO does not engage with PTO
switch activated (raised).
Diagnostic code label is located on right side
console beside operator’s seat.
If starter does not engage, use the diagnostic light (B)
and diagnostic codes (D) to diagnose the problem.
BRAKE NOT ENGAGED (1-2) diagnostic
code: one flash, a short pause and two additional flashes. This code
sequence indicates that the park brake switch has not been activated.
Lock park brake to start engine.
STARTER THERMAL PROTECT MODE (2-5) diagnostic code: two flashes, a short pause and five additional
flashes. This code sequence indicates that the module has started
a 60-second cool-down period to prevent the starter from overheating.
Turn key switch to OFF position and let the starter cool down for
at least 60 seconds before making another attempt to start engine.
Once the unit has started and/or while operating the machine,
the following codes may occur:
NOTE: For safety, the PTO will not engage with the park brake
locked and/or operator out of seat.
PTO/MOW ENGAGED (1-3) diagnostic code:
one flash, a short pause and three additional flashes. This code sequence
can occur when the operator gets out of the seat while operating the
machine with the PTO engaged. This code can be reset by turning off
the PTO (knob) switch.
OVER VOLTAGE (3-1) diagnostic code:
three flashes, a short pause and one additional flash. This code sequence
indicates that the vehicle control unit has detected a voltage higher
than normal in the electrical system. If the problem is severe, the
control unit may disable the PTO output to the PTO clutch. Check electrical
wiring for loose connections, specifically the battery positive and
negative, starter, and frame ground on engine block.
WEAK BATTERY OR STARTER SYSTEM ISSUE (3-3) diagnostic code: three flashes, a short pause and three additional
flashes. This code sequence indicates that the battery may have become
too weak to turn the starter or that the vehicle control unit has
detected an excessive current draw. Recharge the battery. If this
does not remove the code, check that all starter circuit harness connections
are secure and not “shorted” to ground.
OUTPUT FAULT DETECTED (3-7) diagnostic
code: three flashes, a short pause and seven additional flashes. This
code sequence indicates that the vehicle control unit has detected
an electrical problem in the engine wiring harness. The vehicle control
unit's internal “resettable” fuse had tripped to protect
the system. This will remain tripped until the fault is removed. Check
engine wiring harness for pinched or frayed wires.
Refer to the troubleshooting section for additional diagnostic
codes. If further diagnostic assistance is needed, refer to the Technical
Manual or consult your John Deere distributor.
Diagnostic Test Mode
This is a troubleshooting mode that can be used to check the
integrity of the switches, sensors, wiring, and hardware of the vehicle
control unit. The diagnostic information is generated in the vehicle
control unit and displayed through a flashing diagnostic code on the
display module. Please refer to the troubleshooting section of this
manual for more information.