Armrest Controller Unit – The main function of the ACU electronic control unit is to receive commands from the operator and execute the ordered functions by communicating via CAN bus with the corresponding electronic control units. The ACU is a separate electronic control unit located in the right armrest assembly. It differs from other tractor control units in that it does not have a separate mounting box.
John Deere ACU fault codes / John Deere ACU diagnostic trouble codes
NOTE:This page only indicates the meaning of the fault codes. For complete troubleshooting information, see the technical manuals.
ACU 000158.04 (ACU 158.04)— ACU Switched Supply Voltage Low
Code caused by: Armrest Control Unit switched supply voltage below 9.0 V.
Control Unit Response: Function Disabled
ACU 000177.17 (ACU 177.17 )— Engine Speed Limited Due to Cold Oil
Code caused by: Engine speed commanded above 1500 rpm and transmission oil temperature below -5 °C (23 °F).
Control Unit Response: Limits engine speed to 1500 rpm.
NOTE: This code is normal when oil is cold and (-5 °C [23 °F]).
ACU 000237.02 (ACU 237.02 )— VIN Security Data Conflict
Code caused by: Vehicle Identification Number (VIN) from other control units is not the same.
Control Unit Response: Function Degraded
ACU 000237.14 (ACU 237.14 )— VIN Security Not Enabled
Code caused by: Vehicle Identification Number (VIN) security has not been enabled.
Control Unit Response: Function Degraded
ACU 000237.31 (ACU 237.31 )— VIN Security Messages Missing
Code caused by: Vehicle Identification Number (VIN) not received from other control units.
Control Unit Response: Function Degraded
ACU 000581.07 (ACU 581.07 )— Transmission Not Responding to Command
Code caused by: PTI not responding to armrest control unit requests.
Control Unit Response: Defaults to Neutral
ACU 000628.02 (ACU 628.02 )— ACU EOL Data Fault
Code caused by: End-of-line memory failed at start-up.
NOTE: End Of Line (EOL) Data Faults can sometimes be corrected by downloading new software. Attempt to download software for this application.
Control Unit Response: Defaults to Neutral
ACU 000629.11 (ACU 629.11 )— ACU Control Unit Fault
Code caused by: Check of RAM memory failed at start-up.
Control Unit Response: None
ACU 000629.12 (ACU 629.12 )— ACU Control Unit Fault
Code caused by: Armrest control unit software failed to execute in allotted time.
Control Unit Response: Defaults to Neutral
ACU 000630.02 (ACU 630.02 )— ACU Calibration Fault/Data Invalid
Code caused by: Armrest control unit invalid calibration values or failure of calibration memory.
Control Unit Response: Function Degraded
ACU 000630.13 (ACU 630.13 )— ACU Calibration Fault/Not Calibrated
Code caused by: Armrest control unit has never been calibrated or a faulty calibration was saved.
Control Unit Response: Defaults to Neutral
ACU 000974.02 (ACU 974.02 )— Hand Throttle Sensor Circuit Voltage Conflict
Code caused by: Hand throttle sensor circuits 1 and 2 voltage conflict.
Control Unit Response: Function Degraded
ACU 000974.03 (ACU 974.03 )—Hand Throttle Sensor Circuit Voltage High
Code caused by: Hand throttle sensor circuit voltage high.
Control Unit Response: Function Degraded
ACU 000974.04 (ACU 974.04 )— Hand Throttle Sensor Circuit Voltage Low
Code caused by: Hand throttle sensor circuit voltage low.
Control Unit Response: Function Degraded
ACU 001079.03 (ACU 1079.03 )— ACU Sensor Supply 1 Voltage High
Code caused by: Armrest control unit sensor supply voltage high.
Control Unit Response: Function Degraded
ACU 001079.04 (ACU 1079.04 )— ACU Sensor Supply 1 Voltage Low
Code caused by: Armrest control unit sensor supply voltage low.
Control Unit Response: Function Degraded
ACU 001080.03 (ACU 1080.03 )— ACU Sensor Supply 2 Voltage High
Code caused by: Armrest control unit sensor supply voltage high.
Control Unit Response: Function Degraded
ACU 001080.04 (ACU 1080.04 )— ACU Sensor Supply 2 Voltage Low
Armrest control unit sensor supply 2 voltage low.
Control Unit Response: Function Degraded
ACU 002000.09 (ACU 2000.09 )— ECU Message Missing
Code caused by: Armrest control unit not receiving required messages from the ECU.
Control Unit Response: Defaults to idle and disables throttle functions. Commands PARK.
ACU 002003.09 (ACU 2003.09 )— PTI or PTP Message Missing
Code caused by: Armrest control unit not receiving required messages from the PTI or PTP.
Control Unit Response: Commands PARK.
ACU 002020.09 (ACU 2020.09 )— SFA Message Missing
Code caused by: Armrest control unit not receiving required messages from the SFA.
Control Unit Response: Limited Vehicle Speed (30 km/h)
ACU 002049.09 (ACU 2049.09 )— CAB Message Missing
Code caused by: Armrest control unit not receiving required messages from CAB.
Control Unit Response: Defaults to Neutral
ACU 523664.02 — Speed Band 1 and 2 Switches Conflict
Code caused by: Speed band 1 and 2 switches are reading same value.
NOTE: Code is only valid for vehicles equipped with AutoPowr/IVT left-hand reverser option.
Control Unit Response: Defaults to Neutral
ACU 523923.02 — SCV I Control Lever Switch/Sensor Conflict
Code caused by: SCV I control lever switch and sensor voltage conflict.
Control Unit Response: SCV I disabled by SCC control unit
ACU 523923.03 — SCV I Control Lever Sensor Circuit Voltage High
Code caused by: SCV I control lever sensor voltage high.
Control Unit Response: SCV I disabled by SCC control unit
ACU 523923.04 — SCV I Control Lever Sensor Circuit Voltage Low
Code caused by: SCV I control lever sensor voltage below 0.2V.
Control Unit Response: SCV I disabled by SCC control unit
ACU 523953.02 — AutoPowr/IVT Speed Control Lever Sensor Circuit Conflict
Code caused by: Speed control lever sensor voltages 1 and 2 conflict.
Control Unit Response: Defaults to Neutral
ACU 523953.03 — AutoPowr/IVT Speed Control Lever Sensor Voltage High
Code caused by: Speed control lever sensor voltage high.
Control Unit Response: Defaults to Neutral
ACU 523953.04 — AutoPowr/IVT Speed Control Lever Sensor Voltage Low
Code caused by: AutoPowr/IVT speed control lever sensor circuit voltage low.
Control Unit Response: Defaults to Neutral
ACU 523954.07 — Speed Band 1 Adjustment Fault
Code caused by: Calibration for speed band 1 not valid.
Control Unit Response: Limited function
ACU 523954.11 — Set Speed Adjuster Conflict
Code caused by: Set speed adjuster circuit voltage conflict.
NOTE: Code may also be caused by operator constantly changing speed up and/or down one count.
Control Unit Response: Limited Function
ACU 523955.31 — Engine Overload In Manual Mode
Code caused by: Engine load too high in manual mode.
NOTE: Operating an AutoPowr/IVT transmission with selector switch in OFF position could generate code. If OFF position is selected, keep engine at wide open throttle and use drive lever or set speed adjuster to control ground speed.
Control Unit Response: Limited Function
ACU 523958.31 — Reversing Ratio Setting Fault
Code caused by: Ratio between forward and reverse set speed is incorrect.
Control Unit Response: Limited Function
ACU 523960.17 — Operator Not Present At Low Speeds
Code caused by: Operator presence not detected at low speeds.
Control Unit Response: Defaults to Neutral
ACU 523960.31 — Operator Not Seated During Reverser Command
Code caused by: Operator not present and direction commanded.
Control Unit Response: Commands PARK.
ACU 523961.02 — Park Engaged While In Gear
Code caused by: Park on while vehicle is in gear.
NOTE: This code should appear only if PTI failed.
Control Unit Response: Defaults to Neutral
ACU 523961.07 — Park Lock Engagement Fault
Code caused by: Park state does not match the desired state.
Control Unit Response: Defaults to Neutral
ACU 523962.31 — MFWD Speed Incorrect (AutoPowr/IVT only)
Code caused by: MFWD speed invalid.
Control Unit Response: Traction Control Disabled
ACU 523963.02 — Speed Band 1 Switch/Voltage Conflict
Code caused by: Speed band 1 switch does not match analog voltage.
Control Unit Response: Limited Function
ACU 523966.31 — Transmission Come Home Mode
Code caused by: Transmission come home mode enabled.
Control Unit Response: Defaults to Come Home Mode
ACU 523967.02 — Speed Band 2 Switch/Voltage Conflict
Code caused by: Speed band 2 switch does not match analog voltage.
Control Unit Response: Limited Function
ACU 523968.02 — iTEC™ 1/2 Switch Circuit Conflict
Code caused by: iTEC™ 1/2 switch circuits disagree.
Control Unit Response: No iTEC™
NOTE:This code applies to the iTEC™ switch for tractors that do not have field installed kits for dual iTEC™ switches.
ACU 523968.03 — iTEC™ 1/2 Switch Circuits Voltage High
Code caused by: All three iTEC™ 1/2 switch inputs are high.
Control Unit Response: No iTEC™
NOTE: This code applies to the iTEC™ switch for tractors that do not have field installed kits for dual iTEC™ switches.
ACU 523968.04 — iTEC™ 1/2 Switch Circuits Voltage Low
Code caused by: All three iTEC™ 1/2 switch inputs are low.
Control Unit Response: No iTEC™
NOTE: This code applies to the iTEC™ switch for tractors that do not have field installed kits for dual iTEC™ switches.
ACU 524017.31 — Neutral Switch or Forward Slot Voltage Out Of Range
Code caused by: Switch does not clearly indicate a closed or open position.
Control Unit Response: Defaults to Neutral
ACU 524018.31 — RHR Neutral/Park Transition Fault
Code caused by: Lever position transition too long.
Control Unit Response: Commands PARK (PARK Position Recoverable).
ACU 524019.31 — RHR Neutral/Not-Neutral Transition Fault
Code caused by: Lever position transition longer than 5 seconds.
Control Unit Response: Lever Not In PARK
ACU 524020.31 — Transmission In Gear at Power Up
Code caused by: RHR not in PARK at power up.
Control Unit Response: Commands PARK.
ACU 524021.31 — Multiple Reverser Switches Conflict
Code caused by: One or more reverser lever switches have failed.
Control Unit Response: Commands PARK (PARK Position Recoverable).
ACU 524101.02 — Front Hitch Control Lever Switch/Sensor Circuit Conflict
Code caused by: Front hitch control lever switch conflicts with sensor voltage.
Control Unit Response: Hitch is disabled
ACU 524101.03 — Front Hitch Control Lever Sensor Circuit Voltage High
Code caused by: Front hitch control lever sensor circuit voltage high.
Control Unit Response: Hitch is disabled
ACU 524101.04 — Front Hitch Control Lever Sensor Circuit Voltage Low
Code caused by: Front hitch control lever sensor circuit voltage low.
Control Unit Response: Hitch is disabled
ACU 524102.02 — SCV V Control Lever Switch/Sensor Circuit Conflict
Code caused by: SCV V control lever switch conflicts with sensor voltage.
Control Unit Response: SCV V disabled by SCC control unit
ACU 524102.03 — SCV V Control Lever Sensor Circuit Voltage High
Code caused by: SCV V control lever sensor circuit voltage high.
Control Unit Response: SCV V disabled by SCC control unit
ACU 524102.04 — SCV V Control Lever Sensor Circuit Voltage Low
Code caused by: SCV V control lever sensor circuit voltage low.
Control Unit Response: SCV V disabled by SCC control unit
ACU 524103.02 — SCV IV Control Lever Switch/Sensor Circuit Conflict
Code caused by: SCV IV control lever switch conflicts with sensor voltage.
Control Unit Response: SCV IV disabled by SCC control unit
ACU 524103.03 — SCV IV Control Lever Sensor Circuit Voltage High
Code caused by: SCV IV control lever sensor circuit voltage high.
Control Unit Response: SCV IV disabled by SCC control unit
ACU 524103.04 — SCV IV Control Lever Sensor Circuit Voltage Low
Code caused by: SCV IV control lever sensor circuit voltage low.
Control Unit Response: SCV IV disabled by SCC control unit
ACU 524104.02 — SCV III Control Lever Switch/Sensor Circuit Conflict
Code caused by: SCV III control lever switch conflicts with sensor voltage.
Control Unit Response: SCV III disabled by SCC control unit
ACU 524104.03 — SCV III Control Lever Sensor Circuit Voltage High
Code caused by: SCV III control lever sensor circuit voltage high.
Control Unit Response: SCV III disabled by SCC control unit
ACU 524104.04 — SCV III Control Lever Sensor Circuit Voltage Low
Code caused by: SCV III control lever sensor circuit voltage low.
Control Unit Response: SCV III disabled by SCC control unit
ACU 524105.02 — SCV II Control Lever Switch/Sensor Circuit Conflict
Code caused by: SCV II control lever switch conflicts with sensor voltage.
Control Unit Response: SCV II disabled by SCC control unit
ACU 524105.03 — SCV II Control Lever Sensor Circuit Voltage High
Code caused by: SCV II control lever sensor circuit voltage high.
Control Unit Response: SCV II disabled by SCC control unit
ACU 524105.04 — SCV II Control Lever Sensor Circuit Voltage Low
Code caused by: SCV II control lever sensor circuit voltage low.
Control Unit Response: SCV II disabled by SCC control unit
ACU 524212.02 — Rear Hitch Control Lever Switch/Sensor Circuit Conflict
Code caused by: Rear hitch control lever switch conflicts with sensor voltage.
Control Unit Response: Hitch is disabled
ACU 524212.03 — Rear Hitch Control Lever Sensor Circuit Voltage High
Code caused by: Rear hitch control lever sensor circuit voltage high.
Control Unit Response: Hitch is disabled
ACU 524212.04 — Rear Hitch Control Lever Sensor Circuit Voltage Low
Code caused by: Rear hitch control lever sensor circuit voltage low.
Control Unit Response: Hitch is disabled
ACU 524222.02 — Resume Switch Circuit Conflict
Code caused by: Resume switch ON and OFF shows same value.
Control Unit Response: No Action
ACU 524224.02 — Rear PTO Switch Circuit Conflict
Code caused by: Rear PTO switch ON and OFF shows the same value.
Control Unit Response: Rear PTO is disabled
ACU 524254.31 — Transmission Enable Circuit Fault
Code caused by: Transmission enable circuit voltage incorrect.
Control Unit Response: No Action