John Deere Diagnostic Trouble Codes Overview

SPN.FMI Codes Diagnostic Trouble Codes (DTC) are based on the CAN ISO and J1939 SAE Standards. These are worldwide standards for automotive and off-highway vehicles and are controlled by an ISO industry commitiee. There are two main parts that make up a DTC:
SPN - ’Suspect Parameter Number’ - this is intended to identify where the problem exists. An example is ’94’ which the standard defines as ”Fuel Delivery System”. Any vehicles using the ’94’ in the DTC will therefore be defining a problem with the fuel delivery system. The list of possible SPNs is too large to provide here, but basically, codes in the lower numbers (at this time, below 5000) are ’assigned’ numbers that are set standards. SPNs that contain 6 digits, such as 524255 are called ’proprietary’, and are set up in blocks. An example would be 520000 – 540000 which might be assigned to John Deere Waterloo to use for parameters that are not already defined. At some point, if these proprietary numbers are approved by SAE and the CAN commitiee, they may be assigned a lower number and become available industry-wide.
FMI - 'Failure Mode Indicator' - this is a standard set of numbers that defines how the SPN failed. FMIs are defined by the J1939 standard.
By combining the SPN and FMI, the code 000094.03 would mean the Fuel Delivery System input voltage is high. With the universal standard, this would apply to any CAN based vehicle.

ECU fault codes

– The ECU is responsible for controlling the engine.
john deere ecu codes The ECU is responsible for controlling the engine. The ECU accepts signals and commands from various switches and sensors.

EPC fault codes

– The EPC is the controller for PowrQuad PLUS and AutoQuad transmissions.
john deere epc codes The electrically actuated PowrQuad module is the basis for the PowrQuad PLUS and AutoQuad PLUS transmissions.

TCU fault codes

– Control unit for AutoPowr/IVT transmission
john deere tcu codes Transmission control with AutoPowr/IVT transmissionsion

PTH fault codes

– Power Train Hydrostatic Control Unit
john deere PTH codes John Deere power train hydrostatic