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In this article, we explain the main controller–related error codes commonly displayed on
Toyota electric forklifts (8FB10–8FB20 series).

The main controller works like the “brain” of the forklift, controlling all major operations.

When a problem occurs in this unit, the forklift may show the following symptoms:

• The forklift cannot travel
• Load handling (lift / tilt) stops
• Steering becomes heavy
• The forklift moves very slowly (safe mode)

These are critical error codes that often cause sudden breakdowns at job sites.

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■ Indicator Lamp Meanings

• Wrench light flashing
  → A fault has been detected, and the system is limiting operation for safety.
• O/H (Overheat) light ON
  → Overheat protection is active due to high temperature.

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Main Controller Error Code List (A1-1 to AF-8)

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① Voltage & Temperature Errors

A1-1: Main Controller Overvoltage

• Indicator: Wrench flashing
• Description: Voltage is higher than the specified limit
• Symptoms: Travel and load handling stop, steering becomes heavy

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A2-1 (C/R): Main Board Overheat

• Indicator: O/H ON
• Description: Main controller board temperature is too high
• Symptoms: Slow travel (safe mode)

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AA-1: Main Board Temperature Sensor Error (Open / VCC Short)

• Indicator: Wrench flashing
• Description: Possible temperature sensor or wiring failure
• Symptoms: Slow travel

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② Battery & Power Supply Issues

A3-1: Battery Connection Error

• Indicator: Wrench flashing
• Description: Battery cables are incorrectly connected
• Symptoms: Travel and load handling stop, steering becomes heavy

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A3-2: Battery Connection Error (Wrong Voltage)

• Indicator: Wrench flashing
• Description: Battery voltage does not match vehicle specification
• Symptoms: Travel and load handling stop, steering becomes heavy

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A8-1: F1 Fuse Open

• Indicator: Wrench flashing
• Description: Fuse is blown
• Symptoms: Travel and load handling stop, steering becomes heavy

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A8-2: F6 Fuse Open

• Indicator: Wrench flashing
• Description: Fuse is blown
• Symptoms: Travel and load handling stop

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A9-2: F7 Fuse / Solenoid Power Line Open

• Indicator: Wrench flashing
• Description: Power supply line is open or disconnected
• Symptoms: Load handling stops

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③ Safety Devices & Switch Errors

A5-1: Seat Switch Short Circuit

• Indicator: Wrench flashing
• Description: Seat switch circuit short
• Symptoms:
  • OPS function disabled
  • Auto power-off disabled
  • Parking reminder warning disabled at key ON

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A6-3: Tilt Switch Short Circuit

• Indicator: Wrench flashing
• Description: Electrical fault in tilt switch
• Symptoms: Tilt operation stops

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④ Cooling Fan Errors

AB-1: Cooling Fan Overcurrent

• Indicator: Wrench flashing
• Description: Excessive current detected in cooling fan
• Symptoms: Slow travel, cooling fan stops

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AB-2: Cooling Fan Open / Short (80V Models)

• Indicator: Wrench flashing
• Description: Cooling fan wiring open or short circuit
• Symptoms: Slow travel, cooling fan stops

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⑤ Key Start Circuit Error

AC-1: Semiconductor Switch (KEY START) Overcurrent

• Indicator: Wrench flashing
• Description: Overcurrent detected in key start circuit
• Symptoms: Travel and load handling stop, steering becomes heavy

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⑥ Communication Errors with Drivers

AD-1 / AD-2: Drive Motor Driver Communication Error

• Indicator: Wrench flashing
• Description: Communication failure with drive motor driver
• Symptoms: Travel stops, knob position calibration does not work

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AD-5 / AD-6: Pump Motor Driver Communication Error

• Indicator: Wrench flashing
• Description: Communication failure with pump motor driver
• Symptoms: Load handling stops, steering becomes heavy

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⑦ CPU Errors (Main Controller)

AF-1 to AF-4: CPU Error (Severe)

• Indicator: Wrench flashing
• Symptoms: Travel and load handling stop, steering becomes heavy

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AF-5 to AF-8: CPU Error (Unstable Control)

• Indicator: Wrench flashing
• Symptoms: Various control operations become unstable

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Summary

Main controller–related error codes often result in:

• Travel stop
• Load handling stop
• Significant loss of operability

Because of this, they are the highest-priority error codes to check on-site.

If any of these errors appear, we recommend checking the following as soon as possible:

• Battery connection and voltage
• Fuses
• Cooling fan operation
• Wiring and connectors
• Communication with motor drivers
• Main controller unit itself